The eponymous main weapon of the Uchuu Senkan Yamato. Notably, the original Wave Motion Gun itself wasn't just a heroes-only weapon: by season 2, most ships in the Earth Defence Force carried one, and once exposed to the Wave Motion Gun, everyone else tried to copy or modify one. Desslok/Desslar had his Desslok Cannon (said to be weaker than the Wave Motion Gun, but not so much that you'd really notice), and the Comet Empire had their weaker (only one ship at a time) but longer-ranged Magna-Flame Cannon.
Interestingly, the Wave Motion Gun was not treated as something invincible: at the end of the first season, Desslar's one was reflected back at him, and in the second season we have three different incidents of Wave Motion Guns utterly failing in their job (first was the Comet Empire's vanguard fleet flagship firing her Magna Flame Cannon while inside Saturn's ring, only for the energy beam to explode against the rings' particles, giving Earth's fleet the time to reach their weapons' range and annihilate the vanguard fleet; then the Earth Defense Force fired ALL their Wave Motion Guns at the Empire's comet fortress, but failed to do any damage; third was the Yamato finding herself attacked again by Desslar and charging the gun, only for Desslar to mine the space before the muzzle and get a good laugh as the Yamato couldn't fire without being destroyed by her own weapon).
2199 even gives the weapon a longer name: Dimensional Wave Motion Explosive Compression Emitter (though the cast still use the term Wave Motion Gun in practice). And they even explain how it works: by generating Micro Black Holes out of the power from the Wave Engine and harnessing their ability to emit Hawking Radiation bursts, which is actually what shoots out of the gun's barrel.
It also becomes a point of morality in Yamato 2199, where Starsha was horrified that the Star Force had weaponized the Wave Motion technology and almost didn't give them the Cosmo DNA as a result. This was because the Iscandarians themselves had developed Wave Motion Guns before, and went kinda Drunk on the Dark Side (unlike the Yamato crew, they didn't balk at blowing up planets with theirs).
The original Macross Cannon provides the impetus of the plot: the Supervision Army gunship that later became the Macross had been rigged to fire upon Zentradi reconnaissance ships, which it did, prompting the arrival of a full combat fleet. Also, activation of the ship's Fold Engines left the Cannon bereft of power conduits for a while, prompting the iconic transformation (which allowed the Cannon to reconnect with its power source due to the new configuration.)
When the recon ships were fired on, they were below the horizon from the point of view of the Macross. It actually fired through several MILES of the Earth's crust, and still managed to spear the targets through their centers of mass.
By the time of Macross Frontier the concept is increasingly common in the U.N. Spacy fleet, finding itself as the Heavy Quantum Convergence Cannon of the smaller carrier Macross Quarter. Frontier also manages to pack a fully functional (if smallish) Macross Cannon into a fighter! It doesn't have as much oomph as does battleship version, but still has enough power to punch out the Deflector Shields of a capital ship. Also, while the original Cannon was an integral part of the Macross' design, posterior models of similar (and superior) classes modified it into a detachable gunpod. That will be hard to clean up
The Zentradi Mobile Fortresses (Fulbtzs Berrentzs class) were each equipped with a Wave Motion Gun so powerful that any direct fleet engagement essentially boiled down to the question "who will be the first to fire?" This is vividly demonstrated in the original movie where Bodolza is so adamant about opening up on Lapramiz' MF that he willingly sacrifices thousands of his own screening force ships which just happen to be in the line of fire.
The Grand Cannon fired only a single shot in the series. The novelization of the US adaptation of the series states that this destroyed more Zentradi warships than had been lost in the entire history of the species. It makes Dolza change his mind about eradicating the humans and decide he should ally with them against his other enemies. Too bad he'd already laid waste to the Earth and slaughtered most of the population.
The Nadesico, from Martian Successor Nadesico, had the Gravity Cannon. When that got old and stopped working against the enemy, they upgraded to the Phase Transition Cannon.
Arguaby a Deconstruction in the latter case. They fired it once in battle, against live targets (they had been fighting mostly Mecha-Mooks until then, they are so horrified by the ease and scale of destruction unleashed that they never fire the PT Cannon again.
Also from Nadesico, the Cosmos fires 7 Gravity Cannons. This is one of the few times a Wave Motion Gun also qualifies as a spammable attack.
Mobile Suit Gundam and its sequels, spinoffs, and Alternate Universes have a number of these. It's kind of a custom in Gundam now that every series must a huge Wave Motion Gun, sometime even two in one series. It's usually involved in the final battle or close to the end, and destroyed by the heros blowing up its weak point and causing the whole thing to go kaboom.
While Universal Century timeline is usually overlooked in the BFG department, especially compared to Gundam Wing, it is actually better supplied with various WMGs and offers such notable pieces:
The Zeons' Colony Laser is an entire space colony converted into a laser cannon (That's no space station...). The Federation's Solar Ray is a scaled-up version of the mythical Archimedes Death Ray, using tens of thousands of computer-controlled mirrors to reflect sunlight at a target and possessing enough power to take a nice chunk out of the asteroid base Solomon.
The 08th MS TeamOVA. After the failure of Operation British, The Principality of Zeon commissioned the construction of the Apsalus, a Mobile Armor with a beam cannon powerful enough to simply blast through the dozens of meters of earth and rock protecting the Federation's underground Jaburo base.
Unicorn gives us the Beam Magnum, essentially a super-charged version of the standard beam rifle. In the Universal Century, beam rifles have e-packs, effectively energy-based magazines which contain enough energy for roughly seven or eight shots; the Beam Magnum expends all of the e-pack's energy in a single shot, producing a battleship-class particle blast.
In the early episodes, the role was filled by the Noventa Cannon, which barely had a chance to fire once before it was dismantled piecemeal by no more than two mobile suits manned by secondary character pilots.
Next came the cannon mounted to the Fortress Barge space battle station. In keeping with wave cannon tradition, it required a lengthy charging time and roomfuls of technicians to fire properly.
Finally, the weapon mounted to Battleship Libra was the series' crowning achievement in high-velocity destruction. Along with wiping out any number of generic mobile suits, it destroyed not one, but two of the eponymous Gundams. Also, its lengthy recharge time was justified due to the fact that the engineers who designed it built a flaw into the design so that it could not be fired in rapid succession.
Wing Gundam's signature Buster Rifle happened to be a handheld one of these. It's a beam cannon that kills space colonies, but only has enough juice for three shots. Its successor Wing Gundam Zero wielded a Twin Buster Rifle that not only packed twice the firepower, but could be split intoa pair of Buster Rifles and can be fired as many times as the pilot wants! The Twin Buster Rifle is so powerful, that the recoil from firing it 3 times in a row is one of the primary causes of the destruction of the Wing Zero Custom.
In Endless Waltz, there is the Tallgeese III's Mega Cannon, which Zechs uses to destroy the Mariemaia Army's base at asteroid MO-III. Canonically it's almost as powerful as the Twin Buster Rifle, but doesn't have the longevity.
Also worth mentioning is the Vayeate, designed by the Gundam scientists, which carries a large beam cannon that's as powerful as Wing's Buster Rifle, but lacks the ammo restrictions because it's powered by a large energy collector strapped to its back.
Gundam SEED spacecraft of the Archangel (Earth Alliance vessels; specifically, the Archangel and the Dominion) and Izumo (Orb vessels; the Kusanagi) class have a weapon known as the Lohengrin, which is quite close to being a Wave Motion Gun. It shoots a beam of ANTIMATTER at the target, although it's somewhat based in fact: It is a positron beam cannon, and positrons are a form of antimatter that have been proven to exist (they're electrons, but with a positive charge instead of the requisite negative charge). They have to be charged before use, which involves Sucking-In Lines. They're clearly based on the aforementioned Blue Noah version, up to the placement of the gun and charging animations. A long tradition, there!
The GENESIS (from Gundam SEED) is a Wave Motion Gun powered by freakin' NUCLEAR EXPLOSIONS! (Technically it fires a laser made of gamma radiation instead of light)
Gundam SEED Destiny has the Archangel and Kusanagi, which still have their Lohengrins. There are more Izumo-class Orb vessels, as well, meaning there are even more ships with the weapons, as well as artillery versions used by ground forces. ZAFT even gets in on the action with the Minerva, which has the Tannhauser, a positron cannon (essentially a positron beam cannon without the word "beam" in its name).
Remember the GENESIS from Gundam SEED? Well, Gundam SEED Destiny has the Neo GENESIS. It's a smaller, faster-charging version of the original GENESIS, which was destroyed at the end of Gundam SEED. Destiny also has the Requiem, which is a giant beam cannon fired from the far side of the moon (its beam can be redirected with magnetic fields, allowing it to be aimed at virtually anything).
The Satellite Cannons of Gundam X, which had the power required to fire it beamed to it from a base on the moon. The DX has two Satellite Cannons and fires them both at once. It can also fire without almost no cooldown.
The Satellite Cannons have the distinction of being possibly the most powerful Gundam-mounted beam weapon in the franchise. They are anti-army weapons that are so overpowered that they're almost useless for most of the series. The first time the Twin Satellite Cannon is fired, it pretty much vaporizes an island. The first Mid-Season Upgrade the Gundam X gets, in fact, involves the removal of the Satellite Cannon in exchange for weapons more suited to actually killing other Mobile Suits.
Every single one of Tieria's Gundams has at least one One-Hit Kill cannon on it. For Virtue and Seravee, it's the GN Bazooka; for Raphael, they're Seravee II's pincers.
And just like Seravee, Graham Aker's later machines, Susanowo and Brave have the Tri-Punisher, which creates a massive ball of GN particles and fires it at the target.
Don't forget the Gadessa's GN Mega Launcher, or the GN Particle Cannon on Big Bad's mothership with the power to take out an entire fleet.
And of course, Ribbons' ship, the Celestial Being, which fires a beam so massive, it takes an ENTIRE GN DRIVE IN TRANS-AM (albeit a false one) just to fire one shot. And damn is it powerful!
Whenever someone uses Trans-Am, whatever they fire is MASSIVELY beefed up, with no Arbitrary Maximum Rangeat all. Especially visible with the 00 Raiser which fires what looks to be a gigantic sustained shot but is actually a HUNDREDS OF KILOMETRES LONG BEAM SABER. The 00 Qan[T] has an even bigger version longer than the Moon's diameter.
Zabanya's Shield Bits can already cooperate with the Gundam's main weapon to produce Beam Spam but they can also combine into a chain of three rectangular frames that together fire a single crazy powerful shot with a maximum range in the tens of thousands of kilometres.
Then, of course, there's the Gadelaza, which has a beam that can blast a ship big enough for deep space exploration to bits in one shot.
G Gundam goes Up to Eleven with Neo-America's secret weapon- the Statue of Liberty Cannon! It shoots from the torch.
Gundam AGE has the Photon Blaster Cannon on the Diva, spruced up from the AGE Builder.
Which was beefed up even further with the development of the Photon Ring Ray, which in combination with the Photon Blaster can destroy colony sized targets.
AGE-3 has a handheld version of the Diva's Photon Blaster called the SigMaxiss Rifle, capable of killing almost any Vagan mobile suit in a single shot. It even comes with an attachment that acts as a portable Photon Ring Ray that's powerful enough to destroy capital ships.
The AGE-FX has the Stungle Rifle, which has even more power and range per shot than the SigMaxiss Rifle, while being about half the size. It can be attached to a larger barrel to form the Daidal Bazooka, easily capable of punching straight through capital ships.
Not to be left out, the Vagans have their space fortress La Gramis, which can be configured to fire a gigantic beam that can wipe out entire fleets.
SD Gundam Force gives us the end of all examples; ultimate villain General Zeong has a beam that, at full power, can wipe out the entire universe when fired. To put it into perspective, a blast at 0.01% caused shockwaves that can be felt in another dimension.
The Iron Ri Maajon (and a number of other Ri Maajon patterns) from Simoun. Strictly speaking, they aren't guns, but rather Wave Motion Prayers.
The Positron Rifle can manage just two shots in the available time and needs to be slowly charged with all the electrical power of Japan.
There's some reality put into the concept: a positron weapon is a sort of antimatter weapon, and would require truly obscene amounts of energy to function, another example of the limitations put on Evas, including the repeated mentions of the incredibly large budget NERV receives from literally everyone in the world to pay for all that damage and firepower.
The angel that said Positron Rifle is employed against (Ramiel) produces a fusion-powered beam that goes through several buildings. Then it applies more power and fires right through a custom heat shield many meters thick. Next comes a series of blasts that seriously disfigure the surrounding countryside, vaporizing elements of Tokyo 3's point defense system. Finally (when hit by a beam from the Positron Rifle mentioned above), it gets really pissed off and charges a blast that melts away a fairly large mountain.
There's also a Positron Cannon, a combat version of the Rifle (the rifle was a prototype and wasn't supposed to be used at all). Too bad it didn't really help Asuka when facing off against the 15th.
RahXephon had the Vermillion equipped with an assault rifle. While it's primary function was that of a machine gun, the weapon could also fire an energy bolt that exploded with the force of a small nuke.
The title character has three attacks that are basically a magical Wave Motion Gun, the first being "Divine Buster", the second being "Excelion Buster", and the third being the even more powerful "Starlight Breaker." The Cool Starship, the Arthra, also has the "Arc-en-ciel", which is famously used to destroy Reinforce's berserked defense program.
Several of Nanoha's other characters have Wave Motion Guns of their own; Fate and Hayate in particular have their respective attacks "Plasma Zanber Breaker" and "Ragnarok", and the original Reinforce had a virtual arsenal of these attacks, some of them copied from the heroines. Hayate probably still has most of them.
This video shows why Quattro's face was once the page image for Oh Crap (and has been reinstated as the Anime and Manga page image).
More or less, any mage that has the title of "Ace" (Nanoha was already an Ace in the first season) or above have their own versions of the Wave Motion Gun.
Arika's "Bolt From The Blue" in Mai-Otome. Unfortunately, her equal and opposite number Nina has a similarly-powerful attack as well in both her robes. Natsuki also has her Howling Silverwolf attack, debuting near the end of the series in a massive Beam-O-War with Nagi's siege cannon.
Similarly, in Mai Hi ME, Mai's CHILD Kagutsuchi can take out an entire aerial fleet.
The super weapon in Black Heaven falls under this trope as well as being rather hard to activate.
The rifles carried by the gigantic Nobuseri leaders almost qualify, but more properly, the main guns of the Imperial Capital Samurai 7.
The Ideon Gun is one of the most powerful examples, powerful enough to devastate a good portion of a star system. It's particularly fun to use in the Super Robot Wars series, as it can oftentimes wipe out the entire enemy force (and maybe some friendlies) in a single shot if you line it up right.
In the movie Be Invoked, the Buff Clan have their own WMG in the form of a colossal space station that concentrates the energy of a supernova into a beam. It finally destroyed Ideon, at the cost of getting rid of everyone.
Both the OVA and TV incarnations of Ifurita from El Hazard wield a wave motion gun in the form of her "Power Key Staff." How she wields it is probably the crucial difference between the two worlds: OVA-Ifurita is a tragic figure, struggling to balance her nascent emotions with her nature as a living weapon of mass destruction; TV-Ifurita is a massive ditz with a really big gun.
The manga series Blame! features the Gravitational Beam Emitter, a wave motion pistol. Its power is so great that if it were to be used in a regular atmospheric environment (like, you know, ours...), it would have irreversible environmental side effects. Or sowe've been told... The GBE is considered a Class 9 weapon of mass destruction in Blame and is VERY rare to to come across. To give you an idea, at lowest setting, it can shoot a beam 70 km long. Anything in this path is obliterated. At maximum firepower...um...you'd have to see it for yourself.
And the recoil is so powerful that it has a pretty good chance of utterly obliterating the wielder's arm and flinging him like a ragdoll on anything but the lowest setting.
Pretty much every non-mook gun in a Tsutomu Nihei series. The various artificial humans in Biomega all have these; the male lead has two, just in case.
In the Digimon franchise, a few machine-based Mons have these, most notably Imperialdramon (his type isn't Machine if you wanna get technical, but his design is based on Transforming Mecha). He's got three, ranging from "standard finishing attack" through "frag the whole area" to "Combined Energy Attack as strong as a small nuke."
Actually makes sense from a mythological standpoint—Excalibur's legend was derived largely from the sword Caladbolg in Irish Celtic Mythology, a two-handed sword which can emit destructive energy beams.
Hadron cannons in Code Geass, which come in both mech-mounted and battleship varieties (the latter are the really powerful ones). Then there's the Guren's Radiant Wave Surger.
Don't forget the Shen-Hu's Baryon Cannon.
Guchuko from Potemayo has two "horns" on the sides of her head that function like this.
In Zoids, a few Zoid types are equipped with Charged Particle Cannons, usually piloted by Dragons or the Big Bad. Of particular note is the Berserk Fury, which has three charged particle cannons.
In Nausicaä of the Valley of the Wind, the God Warrior's primary weapon is essentially a Wave Motion Gun. Which is of the same design, origin, and firepower as the Eye of the Crypt of Shuwa. The God Warrior and the Crypt even fire their respective beams at one another during the manga's climax.
In Castle in the Sky, Sodom and Gomorrah were but two places destroyed by it, according to Muska.
In the original, the Eagle Unit (one of the three machines that forms the eponymous Combining Mecha) was a small jet that could fire puny laser beams. By Shin Getter Robo it had upgraded itself to a beyond planet sized star-ship, and its laser appropriately became a fleet/planet busting Wave Motion Gun with an energy output high enough to potentially cause a Big Bang.
Shin Dragon in Getter Robo Armageddon has one inside the dragon's mouth powerful enough to blow up one of Jupiter's moons!
Trigun: Vash the Stampede's Angel Arm is a proper, honest-to-goodness wave motion gun. If it gets shot at medium power, it annihilates entire cities. If it's shot at full blast, it carves gigantic craters in other planets. The best part is that it basically consists of a tiny cylinder of Applied Phlebotinum in his revolver. Talk about miniaturization...
The Technique that the leader of the Akatsuki wanted to make with the Bijuu, capable of destroying entire COUNTRIES in an instant. Maybe. Given that the things are really the chakra of some sort of Eldritch Abomination, who knows what that "weapon" really was.
Technically, by nature the Bijuu (and by proxy, their Jinchuuriki) are considered living weapons, capable of unfathomable amounts of mass destruction. Thus, the leader Pain was operating under Tobi's half-truth: the nine Bijuus together could be used to create a weapon that could wipe out entire countries in the blink of an eye... it just wasn't mentioned what EXACTLY the nature of the weapon was... or that the weapon had more or less existed before.
More fitting the trope, the Tailed Beasts themselves can fire an attack called the Bijuudama (Tailed Beast Ball) that comes in the form of either a destructive beam/wave capable of punching through all but the strongest of defenses or a launched sphere with incredible explosive power. At full power Bee's turns a mountain range into a valley. Naruto's is less spectacular, with only half power, but still manages to leave a trail of destruction several miles long.
Now Naruto has full control over Kurama...his Bijuudama puts ALL of Bee's and the other Tailed Beasts' to shame. He can equal a combined one from five lesser Tailed Beasts at once!
The Juubi has two that put Kyuubi's to shame; in its first form, it can fire a Bijuudama that's more like a gigantic continuous laser, which can even be swept to the side while firing to "cut" across a wider area, and able to deflect and set off multiple Bijuudama from the 8- and 9-Tails without being dissipated, while its second form can launch what are essentially cone-shaped Bijuudama ICBMs capable of wiping out the entire assembled Ninja Alliance and then some if it's controller Madara so chose, with a range so high that they can reach just about anywhere on the entire continent, and took out the Konoha intelligence division.
A lampshade is hung on this in Excel♥Saga, where Excel calls the weapon on the Puchuu starship a Wave Motion Gun, in the episode that parodies space operas.
Parodied in Sora Wo Kakeru Shoujo. When Leopard asks Akiha to fire his antimatter cannon — and he's a living space colony, so this is a huge cannon — he prepares for it with bravado. It's a dud. Then played straight when the right components are obtained. The show being what it is, though...
In El-Hazard: The Magnificent World Ifurita's full power gun blast is basically a "nuclear bomb ray." She destroys an entire city with in in the anime, and a mountain in the manga. It takes some time to recharge, but not much.
Evangeline uses one to blow up the Demon God in the Kyoto arc.
One of Asuna's flashbacks reveals during magical war, among (slightly smaller than the above mentioned demon) god soldiers, ancient war dragons, and Magic Knights, battle whale ships that wielded one of these called the divine/spirit cannon. Presumably the strongest artillery weapon in the Magic World, Asuna's Magic Cancel completely eliminated it.
And then there's Chachamaru's Artifact, a freaking Kill Sat she uses to utterly obliterate the Eldritch Abomination that a few moments earlier had cut in half a Gold Dragon like butter.
Guyver has the Giga-Smasher, a plasma cannon whose range, beam width, and power appear approximately equivalent to a Macross Cannon. It's a one shot weapon only, however. It can only be used one time by one of the Guyver's equipping the Gigantic upgrade; One shot with the Giga-Smasher uses up the upgrade's energy reserves and it automatically detaches from the user, leaving them with just their normal Megasmasher and an assload of fatigue.
The Five Star Stories has the Buster Launchers, enormous cannons the bigger of which (starting from the 2 meter caliber) are fully capable of obliterating planets. The common ProwlerSpace Fighter usually mount at least two of these, and as such is considered overpowered, and was replaced by the Mortar Headds planetside. Later, though, a couple of MHs were armed with busters, making them the most heavily armed mechas in the universe.
Mazinger Z'sBreast Fire was always close to this, but Mazinkaiser's Fire Blaster goes all the way when it's fired over the heads of several Mechanical Beasts... and still melts them.
The flagship of the Iron Tribe's fleet is equipped with one of these in Heroic Age. It can destroy and ignite entire planets, causing massive shockwave damage to nearby units. The Az-Azoth fleet commanded by Nilval Nephew also has specialized "core" units that apparently serve no other purpose than to be enormous space-based cannons. Bellcross's rarely used mouth-beam attack also qualifies, as does Artemia's more powerful beam attacks. Finally, the Argonaut has the capability to shift into an enormous gun form, firing a Wave Motion Gun aptly named the "Star Blaster".
Something that has remained fairly constant throughout the various incarnations of Astro Boy is Astro's arsenal. One of his staple weapons, aside from the small laser guns in his fingertips (and the infamous machine gun barrels in his butt), is turning his arms into laser cannons.
In Legend of the Galactic Heroes the fortress Iserlohn is equipped with the weapon "Thor's Hammer" that is more than capable of destroying entire fleets in a single blast.
Battle Angel Alita series 2, Last Order, features a 500 ton Jovian combat cyborg among other things armed with a miniature wormhole connection to the inner parts of the planet Jupiter. You may try to imagine the scale of destruction caused by the pressurized plasma-or-whatever-may-be-the-next-state-of-matter-after-plasma in there being released in a focused beam, but it's probably nowhere close.
Super Atragon: The enemies' giant black cylinders fire lasers that can cut a modern destroyer in half in seconds.
In Iria Zeiram the Animation the burabudin cannon is basically a hand-held WMG. While capable of firing controlled and precise blasts, it can also fire massive continuous beams that can sweep whole armies off the map.
The maduradin cannons are similar to the burabudin, but in vehicle form.
In Vividred Operation, Vivid Yellow's Vivid Engine is a human portable particle accelerator / wave motion cannon capable of vaporizing the show's monster of the week pretty much instantly.
Arpeggio of Blue Steel Super Graviton Cannons. The weakest variants, wielded by Fleet of Fog heavy cruisers, can easily vaporise anything in line of sight, likely up to and beyond low Earth orbit considering their weaker laser weapons can do this. The most powerful are the battleship-class cannons that take up the entire length of a ship and do a significantly scaled-up impression of Moses parting the Red Sea while they charge up; they warp spacetime in their line of fire.
In Yu-Gi-Oh!, there is a card called Wave Motion Cannon. For every turn it spends on the field, presumably representing "charging up", it becomes more powerful by 1000 damage points. When discarded, all accumulated damage is instantly inflicted to the enemy's health bar. As the player's health is 8000 points by default, it can mean an automatic victory for the controller of the card if it spends 8 turns on the field without being destroyed.
The Dark Empire series of Star Wars comics gave us the Eclipse-class Star Destroyer, which has a bow-mounted, downsized version of the Death Star's superlaser. ("Downsized" means "Won't actually blow the planet apart, but will still kill everything living on it.")
All Fall Down has the Reducto-Beam, a colossal shrink ray on the moon that runs on Living Batteries.
The first chapter of Bait and Switch has a brief mention that the Kira Nerys, an obsolete Bajoran patrol frigate that the protagonist served on as a noncom, featured a spinal phaser cannon that took long enough for the bridge to bring to bear against an Orion Syndicate pirate ship that the Orions shot up the ship pretty bad and were able to beam several boarding parties aboard. Once they got it into position, though, it blew the other ship away in one shot.
Star Wars has the Death Star's Superlaser, though the first Death Star only used it to destroy planets. The second Death Star in Return of the Jedi had a superlaser that was better at targeting ships; as Ackbar says, "cruisers can't repel firepower of that magnitude."
Gamera's Mana Cannon, but it also has other nasty side effects—like cutting him off from humanity and draining the health of the earth itself.
Any variant of Godzilla's Breath Weapon, be it Red, Golden or Spiraling Red all count as such. When things are hit with them, they die almost universally and they often rearranges the landscape. Godzilla's usually occur after a brief chargeup period.
In Godzilla vs. Megaguirus, the humans decide to try and use one called the Dimension Tide on Godzilla, which literally fires a Black Hole. Side effects include ripping a hole in the fabric of space and time and creating the movie's main monster.
The surprisingly good Roger Corman B-Movie Battle Beyond the Stars (Seven SamuraiIN SPACE) features a weapon called the "Stellar Converter". It appears to be exactly what it says on the tin, in that when the villain uses it, the weapon appears to ignite an inhabited planet into a small white dwarf star.
The "Hammer", the primary weapon equipped to the city-destroyers in Independence Day certainly qualify.
The Bifrost, properly mishandled, was almost one of these in Thor.
And it had the greatest range of anything on this list, striking through wormholes, though it took longer to get to work.
Half of the super weapon used by the bad guys in the 2009 Star Trek film. It's actually an orbital mining laser used by the Romulans to get Red Matter into the core of a planet.
The Dr. Device/Little Doctor in Ender’s Game, so named because it was developed as the Molecular Disruptor Device. Somewhat different in that it has a short-range area effect rather than being a projectile or beam, but this field can start a chain reaction of apparently unlimited size - it obliterates everything in its area of effect, everything next to its area of effect, everything next to that, and so on until it hits an area without enough mass to continue the chain-reaction. It allows Ender to rewrite the book on military strategy by attacking the enemy formation where its ships are most heavily concentrated. Ender asks if the device could be used on a planet; the response is a horrified shudder. And then he tries it on the Bugger homeworld, annihilating it in a single shot.
In the film, the weapon has a recharge rate of several minutes, and only a single ship is equipped with it. Also, despite annihilating a large Formic fleet, it only turns their homeworld into a volcanic hellhole instead of atomizing it.
The Lensman Arms Race is a trope for a reason. E. E. “Doc” Smith's novel Grey Lensmen features the sunbeam, a weapon which concentrates into a single beam the entire radiant energy output of a star. (And the enemy had plans to extend the principle to novae or supernovae.)
The "primaries", so-called because they're the primary weapons of the ships. When some new (readily portable) tech comes along, those become the primaries and the former primaries become secondaries (or tertiary, and as far down the list as you care to go before they're no longer worth the mass/space to take along). The culmination of this (which happens even before they start throwing planets around) is the one-shot primaries, which are the strongest beam weapons available deliberately overloaded so that they emit one unbelievably strong pulse before exploding. This was initially developed by some Boskonian genius who realized that trading one gun and its crew for one enemy ship and its crew was actually a pretty good exchange if you weren't a member of the gun crew involved. The Patrol, once they figured out what was going on, made it non-lethal (to the attacker) by shielding the hell out of the inside of the turret and operating them by remote control.
In one of John W. Campbell's Arcot, Wade and Morley novels, the eponymous heroes come up with the molecular motion gun, which turns the random molecular motion of an object (heat) into motion in a single direction. The ray is catalytic in nature, so basically any object it is used on, from a city to (in one chapter) an entire star, is a) frozen to absolute zero, and b) hurled off in any direction desired.
The most powerful weapon in the Antares novels is probably the antimatter projector, which fires a continuous stream of antimatter. Not only is it pretty much unbeatable, but it's standard armament for both human and alien blastships.
Stanislaw Lem's Invincible, while having a crew that was at best Mildly Military, certainly didn't lack in firepower. Even its recon planes packed an antimatter gun, and the starship herself could, quoting from the novel itself, "boil a medium-sized sea".
Ed Hamilton's The Star Kings featured a Disruptor — the gun that destroyed the space itself. It ate up a good part of a starship's energy balance, but where it hit, nothing remained.
In Iain M. Banks's Against a Dark Background the Lazy Guns were ancient weapons created by a long dead race that destroyed their target with a suitable dark humoured effect. A person might suffer a heavy anchor to appear above them, or a shark to materialize and bite their head off. A city will be unexpectedly hit by a comet or have a volcano erupt in its main square. The implication is it plucks something from elsewhere in the multiverse and pops it into its own universe where it dispatches the target - with a sense of humour.
In the universe of the Culture, there is such a thing as Gridfire. An adaption of the way that hyperspace engines work, gridfire devices effectively pull the barrier between two universes through real space, resulting in a colossal wall of destructive force appearing as if from nowhere. Smashing planets with it is trivial... one of the characters in Consider Phlebas describes it as the weaponry of the end of the universe. The titular Excession appears to be capable of generating a wall of gridfire perhaps lightyears across with no particular effort.
Other devices are mentioned in passing, and perhaps all spacecraft-grade weaponry counts. For example, Culture warships are equipped with things called "Line Guns" which go largely undescribed but appear to generate transient 1-dimensional gravity singularities... effectively a black hole beam.
In Sergey Snegov's "The Men Like Gods", people use a similar device as an engine. While not initially being all that warlike, they find the side effects of their favorite space drive quite useful later, when rather unfriendly aliens appear. The heroes go on to befriending the crap out of said aliens, in the best Nanoha-style, and then teaming up with them when the next bunch of the enemies arrived. THREE TIMES.
In Ringworld's Children, human starships are armed with a weapon called simply "The Anti-Matter Bullet"; guess what it fires.
In Protector, the Brennan-Monster destroys an entire fleet of Pak warships with something he calls the Finnagle Gun. It fires bowling-ball-sized pellets of pure neutronium.
In The Man-Kzin Wars, the Terran system is defended from invaders by the Mercury Laser; it's a laser the size of the equator of the planet Mercury, and is capable of destroying ships as far out as the orbit of Neptune. It turns out that while a purpose-engineered Wave Motion Gun is fun in itself, lasers powerful enough to drive solar sails are just as grand.
He explains that since he was trying to get away from the Kzin ship, he naturally pointed the drive in exactly the opposite direction: directly toward the Kzin ship. His crew are still pretty squicked by it, because there's considerable evidence he knew exactly what he was doing.
There are a lot of devices like the previous two examples in the era of peace leading up to the first Man-Kzin War. Mining lasers for slagging asteroids that can slag warships just as easily, light-sail launch cannon that can fire coherent beams to the orbit of Neptune, mass drivers for sending material between planets that can just as easily sling chunks of metal at high speed towards invading ships, highly efficient photon drives that double as super-lasers, super-powerful fusion drives for interplanetary and interstellar ships that can spray streams of hot plasma over planetary distances. All of which were key in humanity's overwhelming victory over the Kzinti warfleet in the first Man-Kzin War, since Kzinti telepaths had reported that "humans have no weapons at all." It's all but Word of God that all these technologies were created with a dual-purpose in mind by the paranoids of ARM.
The story "Madness Has Its Place" has as protagonists a former ARM agent and some allies who go to some lengths to arrange that one of them will be at the Mercury Laser station at all times, just in case it needs to be pointed at ... something. It's left somewhat ambiguous whether they actually got away with the plan or were allowed to get away with it, and whether the very existence of the Mercury Laser in the first place is a lucky happenstance or a matter of foresight on the part of like-minded people years ago.
Let's not forget the Soft Weapon, which is an multi-function alien device that can, in one of its modes, convert matter into energy at a distance. It should be noted that this is a hand-held device.
There's also the Wunderland Treatymaker, based on an alien 'excavation tool', it creates two areas, one that suppresses the negative charge of electrons, and one that suppresses the positive charge of protons. The humans made anorbital version. After it was used, they renamed the planet Canyon after its defining feature.
And the Ringworld itself is defended by a laser that is generated from artificially produced sunspots. It shoots a laser beam larger than Earth's moon. The kzin on the team comments, "With such a weapon I could boil the Earth to vapor."
Another of Niven's novels (along with Jerry Pournelle) has some real-world realizable ones: The climactic battle of Footfall involves the Orion-drive powered Archangel Michael (see Real Life section below for a description of what the fuel for one of these suckers is like) that also drops 'spurt bombs' into the drive blasts to power them up. They fire beams of coherent gamma rays. The aliens use landing vessels the size of an aircraft carrier, which are launched back up to orbit on launch lasers. That means they've got ground based lasers with hundreds of times the sustained energy output of the largest chemically powered rockets.
In Jack L. Chalker's Well World series, the entire universe is actually a simulation running on a gigantic computer called the Well of Souls. Humanity figures out how to hack it to a minor degree and builds "Zinder Nullifiers" for use in a major intergalactic war, weapons that basically reformat a large region of space into a default empty vacuum state. The war gets a bit heated, the Nullifiers are overused, and the Well World starts suffering a progressive memory fault that will eventually destroy the entire universe unless our intrepid heroes are able to get into the Well of Souls' control center to fix it.
Colin Kapp's The Chaos Weapon was powered by pulling multiple stars into its ammunition feed; it used a ring of black holes to focus the resulting beam. What this beam did was manipulate entropy: if something bad would ever happen in the target area, the Chaos Weapon could make it happen NOW. Lightning strikes, dams giving way, earthquakes.... You say that star's not due to go nova for another twelve million years? Guess what.
The various Precursor races developed a number of these, especially the Tar-Aiym and Hur'rikku who fought a galaxy-spanning war 500,000 years in the past. One weapon (the Krang) requires a planet-sized power source and creates miniature artificial black holes, while another (the anticollapsar weapon) creates reversed black holes made out of pure antimatter. The latter's unique power source has a charging time on the order of thousands to hundreds of thousands of years, quite possibly a record in fiction.
It gets better in the Grand Finale, Flinx Transcendent. Flinx finds a roaming Tar-Aiym weapons platform that has hundreds of Krangs, which when fired simultaneously can cross the intergalactic void and destroy entire star systems from the backlash alone. Even that isn't enough to affect the Ultimate Evil, though, so he goes and locates a Xunca superweapon that extends across multiple dimensions and pulls in several million galaxies' worth of energy.
The 'Hell-class' weapons from Alastair Reynold's Revelation Space. Some can blast big holes in a planet's crust. Others can destroy stars (or so we're told).
The Hypometric weapons are rather less flamboyant, but in many ways more alarming. They simply cause everything in a specific volume of space to just... disappear. No debris, no radiation, no explosion. The effect propagates at lightspeed, and appears to be impossible to defend against (though perhaps the Inhibitors might have some tricks in that regard).
The Inhibitors have a range of techniques and designs for dealing with troublesome interstellar species. They used one such trick to generate a lethal solar flare and destroy the civilisation on Resurgam. When the inhibitors noticed a new civilisation there, they decided to turn it Up to Eleven and construct a "Star Singer": a gigantic and continuous solar flare that reduces the surface of the inner worlds around the star to slag spoiler:and substantially reduces the star's mass turning it into a red dwarf.
The Andalite Chronicles, a side-story of Animorphs, mentions that a dome ship's main shredder is a laser "as thick as a tree trunk, capable of blasting chunks off a planet".
Stephen Donaldson's The Gap Cycle features the awesomely named Super-Light Proton Beam cannon, which, in addition to being stupendously powerful, is the only weapon in the series capable of dealing Death from Above to planets... we're told. However, despite essentially being the series' main antagonist for the last three books out of five, the weapon is never (successfully) fired. A sort of a reverse Chekhov's Gun. Despite its supposed usefulness, the good guys do not have one — even at the space police headquarters at Earth.
Andrey Livandny's The History of the Galaxy series has the LIGHT annihilation system, developed by the Free Colonies to combat the technological superiority of the Earth Alliance. How it works is not explained, but it acts as a weapon of mass destruction on a planetary scale. As an example, the first time it was used in battle it obliterated a moon and two armadas. Needless to say, it was later more used as a deterrent than a weapon. The reason was stated that the firepower of the weapon could not be adjusted. It simply turned to energy anything in its path with destructive results.
In Mikhail Akhmanov's Arrivals from the Dark series has many alien races using Annihilators (i.e. antimatter cannons), the only defense to which are Deflector Shields. The first novel, Invasion, shows humans get their asses handed to them by an alien starship armed with these, while humans are still using missiles, magnetically-launched icicle spreads, and low-power plasma weapons. The subsequent novels shift the Annihilators into the more common variety of weapons with missiles and magnetic weapons relegated to ground-based use (no one in their right mind would use antimatter weapons in an atmosphere). Plasma weapons remain as secondary weapons for capital ships and primary weapons for fighters.
These also can be used to turn a planet into a smoldering hellhole in about an hour, although this is rarely done, as habitable worlds are valuable.
In the Dale Brown novel Flight of the Old Dog, the Soviets use a laser system rated at hundreds of megawatts for anti-ballistic missile, anti-satellite and basically anti-whatever purposes. The eponymous Airstrike Impossible is carried out to destroy it.
Timothy Zahn's The Conquerors Trilogy has the human's CIRCE weapon, which is capable of completely obliterating any fleet it goes up against. Subverted because CIRCE doesn't actually exist. The first and only battle where it was 'used' was actually won by an insane fluke of luck. The politicians of the allied nations who owned the fleet came up with a fake ultimate weapon as an explanation and used it as a threat to secure their own political power.
Additionally, the Alternate UniverseStar Trek: Voyager story Places of Exile seems to reference the trope itself; shortly after Species 8472 blew up a Borg planet (like in "Scorpion"):
This time they were not so lucky. "The first bioship is on a pursuit course," Tuvok reported.
"Just one? That's a relief," said Paris. "I'd hate to have to take on the other nine and that wave-motion gun of theirs." Janeway assumed the weapon description was another of Tom's obscure twentieth-century cultural allusions.
Hellbores are fusion cannons rated in megatons per second and standard armament on Bolos; the larger Bolos mount several. They were originally developed from weaponry intended for use as the primary armament of space battleships.
Eventually Hellbores were made part of a Bolo's secondary weapons to the point where a Bolo could have over a dozen Hellbores, granted the secondary Hellbores were smaller in size.
Some Bolos were equiped with a Hellbore variant called a Hellrail. These were normally larger than the Bolo's main armament, but could not be depresed to engage ground targets. They were intended explicitly to engage spacecraft. As a Hellbore is capable of pin-point accuracy at interplanetary range, this is a serious threat to any enemny operations in an entire star system.
Special mention must go to the Hutt superweapon, the Darksaber, which was quite literally a Death Star stripped down to the bare essentials, an engine, a powercore, and a superlaser, shaped like a lightsaber. Except it didn't work because the Hutts cheaped out on the construction. Worst. Big Bad. Ever.
In Troy Rising, the SAPL is one. The acronym stands for Solar Array Pumped Laser (the protagonist had a lot of Fun with Acronyms, "SAPL" was intended to also stand for "Serious-Ass Powerful Laser" and was made of various "Very Dangerous Arrays," "Very Scary Arrays," and "Big Damn Arrays" that officially stood for something else), despite it not actually being a laser; it consists of a whole friggin' lot of mirrors in solar orbit, the most critical of which have Lots of High Tech in order to reflect up to petawatts of sunlight without immediately blowing up. The first time they're used, against an alien cruiser that basically took over the Earth in the first chapter, the beam is aimed at a patch of shield that was collapsed by a breacher round. It misses, hits the undamaged front shields, and punches straight through the entire ship.
Then they upped output by few magnitudes. Best part? It was used primarily for orbital mining.
The Mortal Engines Quartet uses them as a plot device with MEDUSA (salvaged from old tech) and then ODIN, the Kill Sat.
Zigzagged in the first novel. Honor is horrified that her ship is stripped of most of its regular armament to make room for one of these. Why? Because it only works at short range, and her opponents can easily blast her light cruiser to smithereens long before she gets there. Then Double Subverted in that the novel conspires to put Honor and her opponent in exactly the situation where she can legitimately use the weapon against him. Then turned back into a subversion with the brass accepting the overall uselessness of the weapon, and electing to not mount it on any more ships.
Defied at some point prior to In Enemy Hands. A Noodle Incident mentioned by Admiral White Haven had saner heads veto an attempt by Admiral Hemphillnote the Mad Scientist who came up with the above-mentioned gravity lance, but also the far more useful missile pods and multi-drive missiles to fit ships of the wall with enormous spinal energy weapons. The obvious problems being A) at this point in the series it's impossible to generate a Deflector Shield to cover the front of the ship, so you're leaving yourself open when you attempt to use it, and B) it would still probably be drastically outranged by missile spam.
The protagonist of Charles Stross's Accelerando uses a "blaster" at one point. Apparently it consists of a wormhole system, one end of which orbits within the photosphere of a star. Pulling the trigger briefly opens the portal, and (rather surprisingly) doesn't destroy everything in the vicinity. Some of the highest levels of overkill in a handweapon, given that the same design could conceivably slag an entire world.
The Hostile Takeover (Swann) series has the Linac, a kilometer and a half long railgun that accelerates projectiles to half the speed of light. It is unique in the universe, not because no one else has the technology to build one, but because no planetary government would allow such a thing in orbit around their planet. Bakunin has no government, so when Proudhon Spaceport Corporation built it, no one bothered to stop them.
The Vorlon Eclipse-class "Planetkiller" seen towards the end of the Vorlon-Shadow war.
The Great Machine on Epsilon III was hinted to be such, and certainly seemed to have the power to do it, but its ultimate purpose was never completely revealed.
The main weapon of the Victory-class Destroyers in the Babylon 5 spinoff Crusade is definitely an example: It's an incredibly powerful (and visually impressive) Vorlon beam weapon that draws so much power from a relatively underwhelming Minbari-sourced power plant (rather than the Vorlons' usual hyperspace tap) that it cripples the ship for a minute after firing.
Also, Earth Alliance has its own variation in the heavy particle beams mounted on combat satellites and the new Warlock-class advanced destroyers (which have two). The satellites had been already hinted to have it in Babylon 5 proper, and when they finally fired (here from 3.20) anything they hit was one-shot into oblivion. On the Warlocks, we only had Word of God about it for a long time, but in The Lost Tales we saw one firing, for obliteration of its poor victim.
According to the Expanded Universe, they acquired the design from the Drazi, a Proud Warrior Race with expansionist tendencies. Thankfully, they don't build warships large enough for it, so they only have it on defensive satellites and space stations, and gave the design to Earth during the Earth-Minbari War for defensive purposes (then again, Humans Are Bastards, and the Earth-Minbari War left them a bit scarred...).
The primary weapon of the Lexx. In fact, the only weapon of the Lexx. Being a living ship and the most powerful weapon in two universes, it's not like the Lexx needs additional firepower. As an added bonus, the CGI effect of the Lexx firing even looks like a wave front.
In the very first minute of the very first episode, there's a rather hellish weapon (the Foreshadow, the flagship of His Divine Shadow) that eradicates the surface of a planet in about 5 shots.
In Star Trek: The Original Series, the episode "The Doomsday Machine" features a miles-long Planet Killer, a conical-shaped machine made of a virtually indestructible material that destroys planets and then uses the rubble to refuel itself. It was theorized by Kirk that the Planet Killer was created as a bluff to keep an all-out war from occurring, but that it somehow was activated and couldn't be stopped, destroying both its creators and their enemies before continuing through the universe. The episode makes a very un-subtle allusion to the H-bomb. In a stroke of irony, it is then stopped by essentially a real H-Bomb — an impulse engine overload.
The navigational deflector dish of the Enterprise-D is modified into one of these on two separate occasions, most notably during "The Best of Both Worlds", where it was used against a Borg cube. It doesn't work, though it would have - the Borg were forewarned and protected themselves against it. It also doesn't work the only other time it was used, to try to free the ship from a Negative Space Wedgie. Other than its complete failure in field testing, the deflector "cannon" features all of the drawbacks of the Wave Motion Gun trope, including long charge times, potential damage to the ship from the firing process, and even the necessity of clearing all the decks surrounding the dish to avoid irradiating the crew. You have to wonder whether the weapon would have fared better if tested on the Enterprise's sister ship... the USS Yamato.
Conversely, the future Enterprise in "All Good Things" features an enormous phaser cannon on the bottom of its saucer section which can destroy powerful Klingon warships with a single shot; it does not appear to cause significant power drain or require a long reloading time.
The Doctor uses a weapon called the "Photonic Cannon" during one of his daydreams. Obviously the Voyager has no such weapon, but they later pretend to in order to scare off a superior foe.
Species 8472 can combine the output of nine ships into one single wave of destruction—which even looks like a wave.
In Super Sentai, and by extension its adaptation Power Rangers, the heavier Humongous Mecha tend to have these. The drawbacks usually aren't mentioned... however, such an attack is usually only used as a finisher or after conventional weapons have already been tried. Rangers themselves can often combine their weapons for a smaller one of these.
In Gene Roddenberry's Andromeda, the big bad has ships equipped with Point Singularity Projectors. Essentially capable of firing off black holes which measure several dozen meters across and can blow holes in anything, from spaceships to planets, to a sun.
The Hand of Omega, in Doctor Who, which isn't even supposed to be a weapon. And that's just for starters. This a series where the final shot of a war erased two races from history.
The Hand of Omega is a weapon in the same sense that any tool is a weapon if held correctly. The less poetic name is the Remote Stellar Manipulator, and is is known to be able to cause stars to go supernova and to collapse into black holes. While USUALLY overkill, incinerating an entire star system is a very EFFECTIVE way to attack anything in that star system.
The Delta Wave from Parting of the Ways/Bad Wolf would have been one of these, except that the Doctor refused to use it because it would have wiped out two races (Humans and Daleks).
The weapon which ended the Time War was called "the Moment"; when fired for the first and only time, it erased all the combatants from time itself, removing them from existence.
In the old German SF series Raumpatrouille, the starship has the aptly-named "Overkill" weapon capable of blowing up small planets.
Though not technically a gun per se, the wormhole weapon in Farscape fits this trope; it makes a freaking black hole.
Lo'La's Weapons Cascade.
The Ori put these as standard armament of their HUGE warships. These things can oneshot a Ha'tak with full shields as well as heavily damaging 304-class ships, potentially destroying them if they can land three hits. Combined with the freakishly strong Ori shields, these guns make Ori ships the spaceship equivalent of Physical Gods.
The Ori ships' pulse weapons are also extremely powerful with three pulses enough to obliterate a Ha'tak.
Asgard plasma beam weapons can also qualify since these are the only weapons known to be able to defeat even Ori ships. And unlike the Ori super-cannon, plasma beam weapons have the same rate of fire but are MUCH smaller to the point where at least four can be fitted onto a single 304-class ship, turning them into Pintsized Powerhouses.
These prove to be useless in the Stargate Atlantis series finale against the super-Hive, a combination of Wraith and Ancient tech. Given that even the Ori motherships can be fairly easily taken down with these beams, this makes the super-Hive the single toughest vessel in the known universe.
And of course there's the Ori satellite weapon. And the much bigger Lantean version that can literally cut a Wraith hiveship in half. Really, the Ancients are rather good at these.
The Asurans have a version of this that involves strapping a hyperdrive to a stargate and sending it to the target location, at which point an extremely-powerful beam is fired at their stargate back on Asuras. The power of the beam can keep the gate open indefinitely (beyond the usual 38-minute cut-off) and also powers the Nigh Invulnerable shield around the "aiming" gate. Essentially, it's a weapon that can destroy anyone without ever leaving home.
There is also the weapon whose sole purpose is bleeding off excess energy from an unstable experimental power source... that blows up 5/6 of a star system.
The Eye weapon built by Anubis for his mothership is capable of fighting off an entire fleet of Ha'taks and destroying the surface of a planet.
Bally's Star Trek pinball game has the USS Enterprise(!) firing one from its front sensor dish.
The Blackstone Fortresses' combined-shot star-killing trick, even the single ship version of their warp cannon.
The aptly named Planet Killer.
Planetside, any gun that fits into the Destroyer weapon class. Typically mounted on Superheavy vehicles, most typically Titans, they are the biggest guns on the battlefield. They don't care if you're insanely tough, incredibly well armoured, or seeking shelter behind a conveniently placed building... Destroyer weapons will vaporize everybody they hit, unless they have a force field that holds up or happens to be immune to being vaporized.
Spinal mount particle accelerators and meson guns in Traveller.
Maulers in Star Fleet Battles, a ship built around a Wave Motion Gun and its associated power systems. Very effective in the hands of a skilled player with a grasp of the right tactics to employ them to their best, less so otherwise.
The Eye of Judgment weapon from Titan-class citadels, which the Shrike was designed to replace, is another one. It's not as resource-efficient, since it requires a crew of 5000 and the Eye is focused by an orichalcum lens a mile across, but the look on an enemy's face as a Titan citadel begins charging its weapon is easily worth it. Yes, someone with a perfect defence will survive, but the surrounding five miles or so will not. And that's radius, not diameter - meaning that as soon as it fires it's goodbye Gem.
Sentinels Of The Multiverse has a hero named Bunker. (So named because of his Powered Armor suit). His main tactic is to play his Omni-Cannon, then sit there for several turns, putting cards from his hand under it. then, he can destroy all the cards under it to deal 2 damage for each card under it. Under most conditions, it's pretty much the most powerful attack in the game.
Omnitron, the giant self-aware robotics factory has one in the form of Disintegration Ray. While not as big or flashy as Bunker's, it can deal quite a bit of damage. Fortunately,it can be broken if Omnitron takes 7 or more damage in a single round.
Yu-Gi-Oh! has a couple of these, such as the much-loved/loathed/feared/dreaded Wave Motion Cannon, which charges up as the turns go by and able to be removed from the field to blast the enemy for 1,000 damage per turn it had charged, Satellite Cannon, a monster that cannot be killed by anything below a certain level and possessing a similar charge-up ability (1000 ATK per turn, loses it after it attacks), and more than one of Seto Kaiba's signature monsters — XYZ Dragon Cannon uses this whenever he discards, and Blue-Eyes White Dragon happens to have this as an attack. Which was later made into a card, namely a Raigekiexpy.
Although Aberrant characters are generally played at a much lower level of power, akin to your average Marvel Comics character, the game has Quantum powers at levels 4, 5, and 6 (which could only be acquired after a very long campaign if you play by the standard rules.) One of the level 6 powers is Quantum Inferno which allows the character to fire a Quantum Bolt capable of punching a hole, hundreds of kilometers wide, clean through the planet (which needless to say is the immediate predecessor to the planet's destruction.)
Dream Pod 9's Jovian Chronicles has them in the form of the Valiant class patrol carriers. These ships, explicity designed for groups of PCs in the vein of White Base and The Macross, packs a high powered laser in a spinal mount easily capable of outright destroying the heaviest capital ships in one shot. Unsurprisingly, it is often referred to the Spinal Laser of Doom.
You can build your own in Mekton Zeta. Mega-Beam plus Charging Time plus Lots Of Kills Worth Of Damage...of course, it'll weigh about seven tons, take up all the space in both your arms, and/or cost a fortune in space efficiency, but just think what it'll do to whatever you point it at.
The ship construction rules have one already pre-designed - the Core Cannon. This takes three full turns to charge and inflicts 1000 Kills of damage. For comparison, a humanoid mecha built at middleweight scale can take maybe 60 kills of damage total (and a maximum of about 12K to any given component before said component becomes shrapnel) with another 60K in armour, meaning a shot from the Core Cannon could vaporise eight times over. Admittedly, with the size difference the Core Cannon is unlikely to ever hit a normal-scale mecha (that's what the Close-In Defence System is for). But it's still absolutely sodding huge and does huge amounts of damage, so it counts.
Thanks to the inclusion of Dragon Ball Z in the Fuzion system (which is directly derived from the Mekton edition of Interlock), Kills scale geometrically. 1,000 Kills is the structural integrity of a heavy striker type starship (about the size of the USS Enterprise NCC-1701, or a modern aircraft carrier). 3,200 Kills is the structural integrity of an Earth-type planet. 12,400 kills and you're one-shotting Jupiter. (reference: )
At peak output the Heavy Disintegrator Cannon from GURPS: Ultra-Tech can instantly vaporize 660 thousand metric tons of any substance per second. That's just the tank sized version, Spaceships has larger ones.
The Action Figure/Card Game Z-G has a special class of weapons intentionally referencing this trope. It is differentiated from ranged weapons by laying down a pattern of cards that hits everyone in the designated "zone". It is called a Zone Weapon.
3rd Edition's Epic Level Handbook introduces the epic spell Vengeful Gaze of God. It has a range of twelve thousand feet and is quite possibly the most powerful offensive spell in the entire game, dealing 305-1830 points of damage, enough to One-Hit Kill pretty much anything (including gods)...and also 200-1200 points of damage to the user.
The comedy game Tales Of The Floating Vagabond has rather simplistic gun rules, however the most powerful guns are labeled "Don't Point That At My Planet!"
The mining laser in System Shock. One shot is enough to turn all of Central Florida to glass.
Mass Effect 2 has the Collector ship's main weapon, fully capable of blowing the original Normandy in half with a glancing hit. Later in the game, you can get the Thanix Cannon, a recent Turian creation, which takes two shots to vaporize the Collector ship in kind. Both these weapons are watered-down versions of a standard Reaper weapon; the beam is actually a constant stream of liquid metal fired at C-fractional velocity. If that description doesn't scare you, look up C-fractional velocity, we'll wait. According to the codex, the Reaper version hits with around the force of 450 kilotons of TNT. To put that into perspective: the Hiroshima bomb had a yield of 13 kilotons of TNT. Not only that, but this cannon can be fired every five seconds and never runs out of ammo.
Super-powerful Wave Cannons a common phenomenon in the R-Type universe (the boss of stage 1 in Delta, Moritz-G, has one, the 'boss' of stage 3 in Delta has two even larger ones, the boss of stage 1 in Final also has one... and so on). A few that're worth noting would be the Utgarda Loki in Tactics, and the Giga Wave Cannon in Final, that can be charged for 7 loops, and instantly destroys any enemy that can die in any difficulty, and it goes through physical obstacles like, say, meteors. In fact, the 'Final' Wave Cannon used to destroy the Bydo Core in stage F-A basically looks and acts like a fully charged Giga Wave Cannon.
Final states that the "planet buster wave cannon" is the same as the fighter mounted wave cannons, but 100 million times more powerful. Given the amount of energy needed to destroy a planet, that means that the fighter-mounted wave cannons have a maximum output somewhere in the region of 100 teratons. No Kill Like Overkill indeed.
The Siege Cannon from Homeworld: Cataclysm, which take several real-time minutes to charge, and even when the fire button is hit, the shot takes an extra few seconds to charge up.
Another weapon seen in Cataclysm, the Repulsor Cannon, can be fitted to Archangel Dreadnoughts and forms the primary weapon of the Nomad Moon in the final single-player mission might be considered one of these, for all that it's actually not all that useful.
Also, the Phased Cannon Array of the Dreadnought and Sajuuk from Homeworld 2.
In Super Robot Wars Original Generation, the capital ship "Hagane" wields a massive, energy-guzzling Tronium Cannon. However, it can be fired with no real recharge time for the ship, and is in fact used often with the 'gravity brake' off so the ship can use the massive inertia in a fancy escape maneuver. The "Hiryuu Custom"'s Gravity Cannon and the SRX's Hyper Titanic Blasting Tronium Buster Cannon also count. Its full name, according toRyuusei, is the Tenjou Tenga Ichigeki Hissatsu hou or Heaven and Earth One-Hit Sure-Kill Cannon.
Super Robot Wars W adds the Valstork's Double Proton Cannon, which can even link with the Valhawk to utilize it's Chest Blaster for even more power. The Dimension Breaker, the Chest Blaster of the Valzacard, by comparison, is its least powerful attack, which, by comparison again, is apparently the Valstork's Double Proton Cannon redirected.
Shin Super Robot Wars has the Hermodr's laser cannon, which destroyed a group of space colonies and acts the primary obstacle in the final scenario of the Space Route. It also appears in the Super Robot Wars Alpha series.
Whenever he's featured in a Capcom fighter, Iron Man has the Proton Cannon, a huge, shoulder-mounted weapon that shoots out a massive repulsor stream. Marvel vs. Capcom 3 adds the possibility to fire the beam at an angle upwards.
Terran capital ships in the StarCraft universe are equipped with a Yamato Gun (naturally, named after Uchuu Senkan Yamato), which fires a massive bolt of energy with massive damage in exchange for a large chunk of the unit's energy meter. This is easily acceptable, though, given the fact that the Yamato Gun is the only use for said energy.
The terran capital ships actually fire a directed nuclear blast. The yamato cannon creates a containment field, detonates a nuclear explosion and then sends the entire package flying at high speeds.
StarCraft II brings back the Yamato Gun (renamed to Yamato Cannon), and also has the Drakken Lazer Drill (only seen in the campaign mission The Dig), a beam capable of taking out a Protoss Archon, which have 300 shields and great defense, in under three seconds. On the Protoss side we have the Void Ray, which should qualify as its initially super-powerful attack becomes stronger over time, and the Planet Cracker, a cut ability for the Mothership.
Interestingly, the Yamato Gun seen in the game and in one cutscene (Emperor Arcturus I's acceptance speech) have different visuals. The version in the game is, basically, a big red blast that travels to the target. The cutscene version is a bright-red energy beam.
It's standard for the Disgaea series to provide any unit that uses a gun long enough with a weapon skill that turns their normally modest weapon into one, Dark Filament from Disgaea 4 probably being the best example (And a Shout-Out to the original wave motion gun).
The Eclipse Cannon that first appeared in Sonic Adventure 2. Also, the Power Laser for Tails' and Eggman's mechs (battle mode and second enemy boss battle only). The former of which is advertised as being powerful enough to destroy planets when fully charged, and delivers as promised in Shadow the Hedgehog.
The Air Force boss and a handful of mechanical mooks have an attack called Wave Cannon that deals heavy lightning damage to all of its enemies. The Air Force uses it after its countdown completes.
Final Fantasy VII features a Mako Cannon, named "Sister Ray", built by the Shinra Electric Power Company for the sake of taking out the impenetrable barrier around Sephiroth. It is fired only once; Diamond Weapon stands in its way and is is cut through, but returns fire, destroying a fair chunk of Shinra headquarters and apparently killing the president. Despite the interference, the weapon succeeds in destroying said barrier.
The player can acquire a summon that calls a being known as Bahamut ZERO, a gigantic flying dragon that bombards its targets from space with a giant beam of destruction.
The prequel Crisis Core brings us Bahamut Fury, which destroys (or at least melts) a good portion of the MOON to fire a giant laser at enemies.
The Guardian Force Eden in Final Fantasy VIII has an attack in which Eden uses the enemy as ammunition for a beam that is fired into another galaxy, which then explodes. It's also powerful enough to break the 9999 HP Damage Cap, which applies to nearly every other attack in the game.
On the subject of Final Fantasy, Sin itself (from Final Fantasy X) should count, given the damage its Tera Gravitation attack causes to the planet when it is fired. Also, the machina that the Al Bhed and later the party use to attack Sin.
Final Fantasy X-2's Vegnagun, which Shuyin tries to use to destroy Spira. It was originally designed to help in the war between Bevelle and Zanarkand, but it was sealed beneath Bevelle when it failed to distinguish friend from foe.
Final Fantasy XII brings us the Mist Cannon, which is deployed at the end of the game against the Rebel fleet, to devastating effect, as it is capable of destroying ANY SHIP IN ONE SHOT.
To emphasize how powerful it is, the Bonus Boss Omega can use their Wave Cannon attack, which usually takes many turns to power up, without charging.
They did at least bother to have the Particle Cannon and Ion Cannon have different firing mechanisms - the Ion Cannon is a satellite-mounted energy weapon, the Particle Cannon is a ground-placed energy weapon that uses orbital mirrors to bounce the beam to the desired destination.
Red Alert 2, for the Allied Prism Tower and Prism Tank. The former can be charged up by other Prism Towers in range with tangible effect, while the latter's Prism Cannon has a flap on the rear which animates when the Cannon is shooting.
The Empire of the Rising Sun in Red Alert 3 has an interesting version in the Wave-Force Artillery. Besides the usual full power blast, it can be turned down for More Dakka.
Possibly Dan Smith's Collateral Shot from Killer7. It's the only thing that can kill the Heaven Smile hives and it uses all the bullets in his gun and three vials of blood.
In Rogue Galaxy, the Dorgenark carries a double-barreled Wave Motion Gun on the front—called, simply, 'The Big Guns'. According to an NPC, they can take out a small planet, and the one time they're used in-game, they live up to the hype.
You do battle against a Wave Motion Gun in Super Mario RPG, controlled by the evil Power Rangers-spoofing Axem Rangers on top of their blade-shaped Cool Ship (if you can call it that) called Blade. It takes 3 turns to charge it up but it has the potential to annihilate your entire party in one turn. Unfortunately, a boss later on in the game has the potential to use this attack every turn.
Super Mario Bros. Z shows what happens when this is connected to a Chaos Emerald from the Sonic games.note For the record, it destroys the entire mountain range of Yoshi's Island. Even the Axem Rangers themselves are shocked. They don't get to use it again though, because Mecha Sonic, the Big Bad of the series, shows up, takes the emerald in question, and singlehandedly destroys them and Blade.
Titan motherships are equipped with doomsday devices, enormous missiles capable of destroying entire fleets of (player) opponents. Even though it's in the hand of a player, this is a last-resort weapon that can only be used once an hour, prevents the Titan from jumping (effectively escaping) for 10 minutes and a single shot is more expensive than some smaller combat vessels. It's also subject to friendly fire (which limits its use to defensive purposes). Before the Obvious Rule Patch doomsdays could be fired remotely, and did not disable jump-drives, making them complete game breakers.
In a more recent update, the Doomsday Device has been changed to a giant laser beam which is used to take out another, usually equally large, ship within a few seconds.
In addition, Jamyl Sarum of the Amarr Empire used a chaining Wave Motion Gun against a Minmatar Titan, destroying it together with it's support fleet. The gun is Lost Technology, MacGyvered into a modern ship hull. Firing it requires some Unobtanium and it melts the ship from within, including the crew. Suffice to say, it's reserved for cutscenes.
The 11th patch/expansion, Dominion, will modify doomsday weapons to be, in the words of Eve blogger/podcaster Winterblink, "Macross cannons": In exchange for losing the AOE damage, they will do massive damage to a single target via a large energy beam. CCP has also hinted that more doomsday weapons are on the way...
Every side has an enormous, Tier 3 artillery piece which takes a half hour to build and fires about once ever 10 or 15 seconds to a range of around 10-15km, enough to cross the small and medium maps and get almost across the large maps (the extra large maps are up to 81km). They're really only useful when used by UEF, and then in large numbers to try and take out the enemy's commander.
The UEF also has a Tier 4 version, which is hideously expensive, has an insane build time, but has unlimited range and much better accuracy then the Tier 3 guns.
The Cybrans have their own Tier 4 artillery, which is cheaper, builds faster, does less damage, and fires fast enough to batter down shields in under 20 seconds, but takes obscene amounts of energy and has much shorter range (though it is mobile, barely).
The Aeon and Cybrans also have tier 4 units that are expensive and slow, but can vaporize everything in front of them with respectively a giant phason and microwave laser. The Cybrans also have the option of upgrading their ACU with one for a massive 5000 DPS. And it can turn invisible. In the expansion, the UEF got a Kill Sat with one of these.
Crysis provides a rather hilariously underwhelming example of this technology when a huge alien space cruiser opens up on a US aircraft carrier, complete with proper "charging" GFX and ominous "buildup" sound. The effect? Several broken bridge windows and some debris on the flight deck. This is made even more ludicrous when the alien behemoth continues the barrage, resulting in no further damage to the ship. One wonders why the aliens didn't just ram the carrier (the cruiser is previously involved in a head-on collision with a destroyer escort, resulting in one sunk destroyer and no apparent damage to the alien vessel). The same alien craft also uses the said weapon on the final level of the Expansion Game where it blasts sections of an airfield before moving on to the carrier.
The Jehuty gets one in Zone of the Enders: The Second Runner, called the Vector Cannon. It takes an absurdly long time to fire, but rest assured that whatever's on the receiving end of it will die.
Bungie's Oni also features the Wave Motion Cannon, an absurdly BFG that was originally a part of a combat vehicle. It can either shoot a long, laser-like energy beam or launch grenades (and yes, each firing of the energy beam requires a few moments of Sucking-In Lines) The Cannon was previously Dummied Out of another Bungie game, Marathon. All that survived in the data files was its name, leading to Wave Motion GunWMG.
To defeat Adam, the final boss of Headhunter, you first need to steal his 'Judgment Cannon', a massive hand-held Wave Motion Gun, charge it up by Sucking-In Lines, and blast it in his chest, hoping that he doesn't stomp up and hit you while you're vulnerable.
In Space Empires V, and its predecessors, a weapon available for ships is a literal Wave Motion Gun, which is a powerful, long-range beam weapon.
The Savior boss's ultimate attack from Devil May Cry 4 is of this variety.
In the same game, Dante obtains a portable version in the form of the PF398: Revenge, one of the (seven of) 666formsPandora can assume. Any non-boss enemy on the receiving end of this laser is all but assured to be reduced to ash. Beyond that, whipping it out on the aforementioned Savior is one of the easiest ways to instantly incapacitate it so that Dante can go in for the kill. Have fun.
The #3 ranked assassin Speed Buster in No More Heroes wields a shopping cart... which transforms into an all-annihilating Wave Motion Gun.
Gorgon (the "Area 6" boss) with its giant rainbow laser.
And the Saucererer, with its Katina-base-destroying laser that takes a full minute to charge up.
In Koei's Warship Gunner series, basically Dynasty Warriors with battleships, the most powerful weapons in the game are "Wave Guns," which come in several sizes but all of which fire lasers larger than the player's ship (which cause the player's ship to rocket backward thanks to laser recoil) and can sink fleets of enemy ships, yet will do fairly little against the game's island-sized bosses, who can have multiple wave guns and giant, hull mounted instant death buzz-saws.
In the space flight simulation FreeSpace 2 most capital ships are equipped with up to a dozen very powerful beam weapons. They have a both visual and audible buildup of 3 seconds and fire beams that can blast straight through other ships. Their diameter is large enough to completely engulf smaller fighters, which are instantly vaporized if they happen to be in the beams path at the moment. This can lead to some irritating deaths where your fighter just happens to be in the path of one of those beams: the capital ship beams do not target fighters, but heaven help you if you decide to fight in between two opposing capital ships, because they hit instantaneously and are therefore undodgeable.
The TEC's Novalith Cannon. The best way to describe it is that it does to planets what nuclear bombs do to cities. A single hit will depopulate all the but the most heavily populated planets. For those, you need two missiles. Oh, and there's fallout.
Also, one of the Advent capital ships has one of these as its "capstone" ability, Cleansing Brilliance.
Likewise, the Vasari Kotsura Cannon applies.
Possibly the Advent's Deliverance Engine, which essentially fires weaponized love. Kinda.
When you pilot the Super Dimensional Gear for a single battle in Xenogears, you can opt to fire the Yggdrasil cannon for 9999 damage. The only drawback is that it costs 9000 of your 9990 fuel.
Xenosaga has several. There's the Phase Transfer Cannon KOS-MOS uses, for starters. Then the Dammerung has a huge version called the Rhine Maiden designed to be fired in conjuction with three other ships. Note that this is huge in comparison to the Dammerung itself. Also note that the Dammerung is huge, with dimensions measured in kilometers.
Don't forget the Durandal, which has beam weaponry capable of wiping out an entire fleet of Gnosis within seconds. And then there is KOS-MOSherself, who's pretty much a walking Wave Motion Gun. Her most powerful attack, the X-Buster, was one of the only few that got an in-battle video sequence in Episode I.
Heavy Beam-class weapons in Sword of the Stars, ranging from the Heavy Combat Laser to the (anti-matter) Cutter Beam. Firing one on a planet leaves a large canyon, and Dreadnaughts can carry up to fourteen of them.
Iji gives us the Phantom Hammer, a ship-mounted energy cannon that, used in numbers, can either render a planet uninhabitable, or destroy it completely. A shot from one of these can pierce through several kilometres of solid rock. The final boss carries a more compact version; it's no less powerful.
If Iji cracks together the two most powerful pieces of Tasen and Komato nanoweaponry, she gets the Velocithor, a hand-held Wave Motion Gun capable of blasting through enemies and walls alike, and is instrumental in a very specific bit of Dungeon Bypass.
In the RTS Rise of Legends, the Cuotl race have practically built their entire society off of Wave Motion Guns. Oh, and machines made of stone. But really the Frickin' Laser Beams.
In the story mode, the Subspace army manages to pull what amounts to a huge gun with mounted turrets on its side out of subspace. Its about 10x the size of the Halberd, the annoying ship you chase for most of the game, and that ship is already hundreds of feet long. This floating gun fires a huge energy blast that pushes the entire world into another dimension!. Shortly thereafter destroyed by Kirby, riding a tiny Air Ride Machine. Miniature airplane trumps world crushing battleship. Who'da thunk it.
Smash Bros has a lot of WMGs. Lucario's Aura Storm, Mario's Mario Finale, Ho-oh's Sacred Fire, Deoxys's Hyper Beam, Red's Triple Finish...
Samus' Hyper Beam from Super Metroid, which is actually an attack taken from Mother Brain by the now-adult-sized Metroid that you saved on SR 388 in Return of Samus, who, after realizing you are its mother, gives it to you after draining Mother Brain of (most of) her energy. It is only used for a short time during the final boss fight and brings the once-powerful creature to its Yugo-sized knees.
The Stellar Converter, which can only be mounted on ships of Titan class or largernote With enough miniaturization, one can fit a Stellar Converter on a Battleship. However, by that point in the game, one would be forgiven for asking "why bother". If the player has survived to that stage in the game, using SC-armed battleships is just demonstrating Video Game Cruelty Potential., is the most powerful beam weapon in the game, and can indeed be used to destroy entire planets. It can also be built on planets as a defensive weapon.
The most powerful beam weapon in the first Master of Orion, by a factor of ten, is the Death Ray. Obtaining it mid-game is very feasible (unless Orion is on the far side of the galaxy, or you're in the middle of a hot war and can't spare the battleships), and at mid-game tech levels the weapon is so large and has such high power requirements that one instance of it may or may not fit into an otherwise empty cruiser hull. It is also powerful enough to take out an enemy cruiser in one shot, almost regardless of shields or armour (extra-heavy neutronium will sometimes withstand it), and is the only beam weapon guaranteed to be effective against planetary defenses all the way through the game. Note that the Stellar Converter from the second game shares only the name and enveloping damage with the first game's Stellar Converter. In the original Master of Orion, the Stellar Converter is merely longer-ranged weapon, with no Earth-Shattering Kaboom effect on planets.
You don't get to use one in Gradius except maybe for the E-laser in Gradius V, but they certainly get used against you. The idea generally isn't to dodge them (which is fairly easy) but to keep from getting forced into a very bad place by the beams (which isn't).
Fraxy gives you the Laser in 3 different sizes and the Sonic Wave, which pushes people away.
Star Wars: Empire at War and Forces of Corruption expansion: First and foremost: Both Death Stars. Then, there's the plasma cannons of the Zann Consortium space stations, Aggressor-Class battleships, and MZ-8 tanks. Captain Piett's Star Destroyer (the Accusor) also gets a Proton Beam weapon in both games.
The last mission of the expansion campaign features the Eclipse Super Star Destroyer, fitted with a weaker version of the Death Star's planet-busting beam. It can One-Hit Killany ship and is very useful, since you have to fight both The Empire and the Rebel fleets. Conveniently, the beam stops working just as another SSD jumps into the fray, so you have to destroy it by conventional means. The Star Wars Expanded Universe novels indicate that the Eclipse could easily take on a large New Republic fleet on its own and win.
Another Star Wars example. The Mass Shadow Generator in Knights of the Old Republic. Turned Malachor V into a mass grave, killed most of the Mandalorians and all but one of the Jedi in proximity (and said Jedi had to go Force-deaf to survive it), and was so destructive that even the Mandalorians were horrified by it.
Not a laser, but Ace Combat 6 has the giant railgun Chandelier as its Final Boss. It normally takes a long time for it to fire one of its shots (about a minute and a half between "Stauros Preparing for launch" and the giant flash of the cannon firing), but when the crew realizes all is lost, failing to take it out then and there leads to the cannon firing 10 shots (and failing your mission) in a row before it collapses.
And then there's the Excalibur in Ace Combat Zero, which is a laser, the Arkbird's laser cannon in Ace Combat 5, and the Stonehenge railgun array in Ace Combat 4.
Ace Combat 5 and Ace Combat Zero also have unlockable planes with laser cannons as special weapons, the ADF-10A/F Falken in both, along with the ADFX-01/02 Morgan in Zero
Ace Combat 3 has Rena's X-49 Night Raven, with a laser that can destroy an island in one shot. The playable version is toned down though.
Ace Combat X: Skies of Deception has both a wave motion gun (the Shock Cannon of the Gleipnir airborne fortress) and wave motion missiles (the same fortress' Shock Wave Ballistic Missiles).
In the same vein as above, Air Force Delta Strike features the Leupold Battery of guns so large, you have to fly down the barrel to destroy it. There are three of them.
Armored Core 4 has the Kojima cannons, massive Phlebotinum shooting beam weapons charged by Sucking-In Lines, that if they actually hit are an instant kill. Unfortunately, outside of two missions in for Answer,they're useless.
And in For Answer there's the Assault Cannon, Lethaldose, a Kojima Cannon of immense power that instead of having the traditional charge time of a Kojima Cannon, it uses your Primal Armor instead, which then takes a long time to recharge.
The series' signiature weapon, the KARASAWA (renamed CANOPUS) laser rifle, is one of these, generally the single most powerful energy weapon in its given game. In Armored Core 4, a middleweight craft wielding two of these can S-Rank the infamous March Au Supplice mission with ease, provided the player is experienced enough. Of course, in every game, they are severely hampered by their weight and the amount of energy they consume with each shot.
G-Darius has the Alpha (player-fired) and Beta (boss-fired) beams. The scary part is that they can absorb each other, and by doing so become larger, more powerful, and longer lasting. Enemies must be captured and consumed in order to fire your Alpha beam, and certain powerful enemies will make your Alpha beam more powerful.
In Spore, a player who has made certain choices progressing to the space stage will gain the racial ability to unleash the Gravitation Wave, which will destroy all structures on a planet. Anyone can research a planet-killing laser though. The use of either of these weapons is pretty much the only thing which is outlawed on a galactic scale and will piss off any neighbors close enough to detect it.
This is in Space Channel 5, of all series. Everyone you saved helps you charge up a super huge laser to take out Blank/Purge depending on which game you're playing. However, you have to hit all three "chus" that the villain gives you, or it's the bad ending for you!
In the Thunder Force series of games, the Rynex-class starfighter can be upgraded with the Thunder Sword that requires several seconds for the spherical CLAW drones to charge up to full capacity and fires a huge beam with a comparative short range that will annihilate standard enemies in its path and can inflict heavy damage on Boss encounters.
In several Kirby games, Kirby gains the power Crash. This power will destroy anything on screen, provided it is not a boss or a miniboss. Fortunately, this power can only be used once, preventing it from becoming a Game Breaker.
X2: The Threat and X3: Reunion have the Phased Shockwave Generator, which is a Game Breaker. Instead of firing a single energy bullet like most weapons in the game, it fires an expanding wavefront that is actually more deadly against capital ships, since it can hit them multiple times with a single shot. In X2 a single fighter with three Beta PSGs could destroy almost any ship or station en masse. And then there's the Paranid Zeus, which can mount eighteen of the things... (It is a heavy capital ship.)
The PSG was thankfully reduced to capital ship only in X3: Terran Conflict. Now the best contender for Wave Motion Gun is if you fit a Boron Thresher frigate with fixed forward facing Photon Pulse Cannons, which lets a player-piloted Thresher snipe capital ships quite effectively. A Thresher so equipped is a Glass Cannon however: in addition to the class having below-average shielding, you can get off maybe two or three blasts from your main guns before you've completely depleted your energy reserves.
Mystical Ninja Starring Goemon, on the N64. A surreal fantasy-action-adventure set in semi-mythological semi-feudal Japan, like a simplified Ocarina of Time but with a seriously twisted sense of humour. Some of the bosses are giant alien war mecha that you fight from the cockpit of a giant war mecha of your own called Impact, which looks like a giant grinning robotic Goemon. Impact can charge up a huge energy cannon by causing damage to a boss with conventional attacks; firing this cuts to a cool exterior shot of the beam slamming into the boss and knocking it backwards. Three or four shots of the Impact Cannon are usually sufficient to do away with even the end-game boss, which is effectively a Death Star in the shape of a giant peach and has a wave motion gun of its own...
Front Mission 3 has the Heavy P-Gun, a prototype beam weapon that exists on two bosses and can also be acquired by the player through a subquest. It's capable of destroying most wanzer body parts in one shot, often resulting in a one-hit KO against a target, but the action point cost to fire it is so high it often can only be fired once every other turn.
In Astro Boy: Omega Factor, you have the Arm Cannon (mentioned above in regards to the Astro Boy anime & manga series), which, when fully upgraded, has an area that takes up around half the screen. The game even identifies this in the introductory stage as Astro's strongest weapon.
In Kingdom Hearts II, Xaldin shoots you with a wind blast gun. Ansem also does it with darkness.
Warblade has a long string of different weapon upgrades Then, halfway through, they become fairly close to this. You have the standard single, double, triple weapons that appear all the time in other space-invader-style shmups, then quadruple fire, which is a bit Up to Eleven for some people. Then there is an upgraded triple fire, then plasma, which shoots a blue ball of energy, followed by fireballs (a wave motion gun in itself), then a laser, and finally upgraded plasma which is like normal plasma but has a wider spread and melts absolutely everything. And that's WITHOUT Super Autofire, which pretty much quadruples firing rate. It's probably safe to say that if you pick up a triple shot powerup if you have something really awesome, you are totally screwed.
The Sega Mega Drive game Ranger X features the Solar Mining Cannon, which covers 2/3rds of the screen and blows the camera forward instead of sending the eponymous Ranger backwards as might be expected.
In Dungeon Fighter Online the Launcher subclass actually gets two. One is his/her bread-and-butter Laser Rifle, which can be charged into not only a larger laser, but causes the rifle to expand. The other is a technique that starts off as 4 separate rotating beams, then merges into a more powerful one. Fired by a Kill Sat.
The so-called "Turbo Attack" from Gauntlet: Legends and Gauntlet: Dark Legacy. Although the Turbo Attack is actually a magic spell and not a technological device, it fits the trope in every other way.
The Particle Beam Smart Bomb weapon in Lightning Fighters.
The makers of Infinite Space sure love their WMGs. You've got both Krebs, the ZR, the ZR 2, Project Stetalumo, and that's even before you get onto the ones that you can actually use, namely the High-Stream Blaster (which is apparently an antimatter cannon) on the Corsair, Mayr and Evstafi, the Surface Blast on any number of ships (the Zanetti is the one that comes to mind) and the Meteor Plasma on the Freedom. Unfortunately, the ones you can use are a bit rubbish, and once you get to the later stages of the game, even one volley from your fleet is way more powerful, if much less awesome.
Final boss Z-Gradt has the largest one of all, in which a giant cannon extends from its body and tracks the player. After a moment, it fires a giant beam that can severely damage any mech, and is particularly devastating to the more lightly-armored ones. As its health gets low, it can even fire this beam while still moving, and tends to back itself away into a corner to try and prevent the player from simply walking around it to dodge. Unfortunately (for Z-Gradt), it is extremely vulnerable to all attacks during this phase.
In the same game, hidden boss VR-Jaguarandi has a variation of Raiden's cannon, unforgiving on players that get caught in it.
The Leviathan from Conduit 2 is a gigantic sea serpent who shoots a massive laser beam from its mouth.
The Shock Beam cannon in Battleships Forever adds a damage multiplier to the base damage when fully charged, causing it to deal +150% damage while making the beam much larger.
The Legend of Dragoon has 2, the first one being the Black-Burst dragon's shadow cannon, and the second one being the infamous divine dragon cannon.
The Tale of ALLTYNEX series uses this in all three games in various shapes and forms. A special note goes to the ZODIACs, whose laser blast sometimes cover the entire screen.
Stage 6 of Hellsinker features a huge beam coming from the bottom of the screen as a setpiece. While the player isn't in control of the beam, enemies also take damage from being hit with it, and it can be used to break through walls or even kill the midboss.
And let's not forget Kaguras "Xanthez" discharge. The thing has the shortest duration of any discharge in the game but is also the most powerful.
Three major versions exist in Escape Velocity Nova. There's the Vell-os psionic weapons, including the "turreted" Autumn Petal and the even-deadlier fixed Winter Tempest. The Aurorans get in on the action by importing Vell-os tech, applying their standard Tim Taylor-meets-Worf design scheme to it, and create the Thunderforge dreadnought and its "Triphammer" main guns (also qualifies as an example of More Dakka). Meanwhile, the PolarisCapacitor Pulse Lasers were just as deadly as either and vastly more common, being mounted on all their capital ships save the Dragon (frigate analog).
The Brahmastra from Asura's Wrath It and the Karma fortress it resides in are powered by human souls. It ends up being fired twice: Once at the intended target, Gohma Vlitra, a continent-sized monster that the Guardian Generals/Seven Deities have been fighting for eternity. All it does is piss Vlitra off. Later, it gets fired at Berserker Asura, who by this point is singlehandedly destroying the Deities' entire fleet. It manages to damage Berserker Asura's extra arms and force him into the less overly destructive but still horribly powerful Wrath form.
The Pokémon games have some, the most known of which is probably Hyper Beam and its variations. Due to its nature, most are more likely to use the more practical wave motion guns available to them such as Flash Cannon, Dragon Pulse, and Solar Beam (in the sunlight), etc. Needless to say, the franchise has built up a Wave Motion Arsenal.
In Tales of Eternia, Fog/Max's Elemental Master arte turns his gun into one by firing a laser that covers the length of the entire battlefield and almost reaches the top of the screen.
In Skies of Arcadia, when you fight DeLoco for the second time, his ship has a Moonstone Cannon prototype that unleashes a giant yellow beam of death. Once you get your own ship, it comes with the full version.
The Gravios and Basarios from Monster Hunter have one of these as their breath weapon in the form of a giant heat beam. The third installment in the series upped the ante even further with the Agnaktor, which is basically the Gravios' heat beam put into a high-speed frame.
The alien ship's death ray in Fallout 3: Mothership Zeta. At one point, the aliens fire it on Earth. In the quest's final battle, you use it against another alien ship. The Tesla Cannon in Broken Steel is one of the smaller man-portable type.
The Sectopods in XCOM: Enemy Unknown are equipped with no less than two. They are smaller than most examples, but since they're only being used on modern humans and their technology, that's perfectly fine. They are one of the most powerful weapons in the game (second only to the claws of a Berserker), and what makes the WMG's really bad is the Sectopod's ability to fire twice in one turn at separate targets AND set up Overwatch to shoot any of your soldiers if they move. Combined with their health (highest in the game) and high defense that makes it hard for your troops to hit, and you have the strongest, most feared enemy in game.
The "Hellball" spell in Neverwinter Nights 1 probably qualifies for this trope because it's the most powerful Area Of Effect spell in the game and although it acts as a Guided Missile, it takes time to reach the enemy giving them time to kill you first, and also if you don't back off immediately after casting, you'll be caught in the blast and suffer its effects as well.
A few enemies in The Binding of Isaac have wide beam attacks, particularly Gluttony, who rips open his chest and apparently fires a massive beam of his own blood. The player can get this attack for themselves, and it is quite deadly in exchange for charge time. You can find a power-up called Shoop Da Whoop, which does exactly what you'd expect.
Star Trek Online: The Galaxy Dreadnought Cruiser, a copy of the three-nacelle Enterprise-D that appeared in TNG: "All Good Things...", features a spinal phaser lance that can do incredibly high amounts of damage ... if it hits. In practice it's decidedly Awesome, but Impractical: Its firing arc is narrow* wouldn't be a problem except the turn rate of the Galaxy-X is terrible for any Fixed Forward-Facing Weapon, its accuracy is horrible, it causes massive weapons power drain, it has an absurdly long cooldown, and it basically locks you into using phasers for your primary weapons if you want to max out its damage.* Damage booster consoles that affect a particular energy type (e.g. phaser, disruptor, antiproton) are more effective than ones that affect a weapon type (beams, cannons, torpedoes, or mines). Not to mention min-maxers have duplicated its high damage with the much more usable Beam Overload bridge officer skill.
To add insult to injury, the Nausicaan Guramba Siege Destroyer has a similar disruptor javelin which is almost as damaging but has a third of the cooldown and no accuracy limitation, making it much more usable.
In Bob and George, Dr. Light has a Wave Motion BB Gun. It requires three hours of charging and half the power of a city, but it can accelerate a BB to relativistic speeds. It's the perfect thing to use on gnomes. When George asked why he never used it before, Dr. Light had only this to say:
Dr.Light: Jesus, George, it's just a harmless BB Gun!
Ship to ship combat in Angels 2200 seems to consist of capital ships firing their particle beams, powerful laser cannons that can blow right through another ship, at one another, then letting the fighters duke it out while they wait for the beams to recharge.
King LOTA's new toy, in Schlock Mercenary, can shoot you from the other side of the galaxy as long as LOTA has targeting information. Shields won't help, either, but not because it'll punch right through (though it certainly could), but rather because it bypasses them entirely.
Kevyn: This is where I defecate in sympathetic reflex for every defense planner in the galaxy.
In Touhou: a Glimmer of an Outside World, the already ridiculous lasers featured in canon get turned up to eleven with Twilight Spark, and Ultimate Spark. The latter is four already massive magical lasers in one.
Mother of Invention in Red vs. Blue Season 9 has the standard frigate MAC cannon, but it was animated such that it appears to be one of these. On screen, it's killed three Longswords and one skyscraper. Lengthwise.
Quite common in Void Of The Stars. It's what you get when you don't activate the bow particle tractor on the Warp Drive. Also the Antiproton Streamer, which fires a solid stream of antiprotons at the target vessel.
The Archai of Orion's Arm have a large number of stupendously destructive weapon technologies available to them, but one that exists only as a rumour is the Thunderbolt... a singularity that propagates at the speed of light (so by the time you've seen it, it is too late to actually do anything about it) and effectively destroys spacetime. No-one really wants to think about what sort of opponents would be so terrifying that a weapon that appears to worry even the archai was needed to defeat them.
As befits is quite hard scifi nature, the Thunderbolt was based on real-world theoretical physics, see below.
The flagship of the Irken fleet in Invader Zim, The Massive, has one of these as its main weapon. Also seems to be present on their Humongous Mecha.
Both on the Megadoomer Stealth Assault Mech and the Maimbot. Also worth mentioning is the "Death Wave Cannon" mentioned by the Tallest in the beginning of episode Hobo 13. Although never shown in action, this cannon seems to be a Wave Motion Gun of its own.
In the final episode the giant robot Dib pilots has 2 cannons one in its chest the other in its hair.
The Malevolence, General Grievous' flagship from Star Wars: The Clone Wars, is equipped with a pair of gigantic ion cannons that each produce a blast so huge that they can hit an entire starfleet. It's a bit different from the standard Wave Motion Gun, though, in that it only disables enemy ships, rather than destroying them; the ship then actually finishes them off with its immense array of turbolaser turrets.
The eponymous Iron Giant has one in its chest. It missed, but by all indications the blast would have been powerful enough to destroy a battleship in one shot.
The secret organization in Sym-Bionic Titan has such a weapon. It's even called a Wave Motion Cannon.
The last actual episode of SWAT Kats to be aired featured a gun developed at the weapons lab with the power to stop earthquakes from space, and then look what's coming along assimilating all the technology it can...
A hypothetical real-life Wave Motion Gun would be Nuclear Shaped-Chargeweapons. It believed that the needed technology does exist (Project Orion wouldn't have been considered without them). Basically, instead of wasting 90% of a nuclear weapon's output in an undirected explosion that would mostly miss the target, a bit of engineering ensures that a good 85% of the energy is radiatied into a ~22.5 degree cone. Suddenly, the kill range for nukes in space goes from a hundred metres to tens of kilometres, and serious damage could be inflicted from hundreds of kilometres away all without needing anything that couldn't be made in the 70s.
It isthe concept behind the Yamato Cannon. Project Orion long predates Starcraft.
Combine Wave Motion Gun with Beam Spam with Recursive Ammo and you get Project Excalibur, a theoretical X-ray laser Kill Sat powered by a nuke going off that Edward Teller thought up for ballistic missile defense. Eventually folded into SDI, but never left the drawing board after disappointing preliminary tests with X-ray lasers.
Excellent real-life example of what an unusually powerful GRB is capable of: the Oh-My-God particle. This is a proton with 300 EeV kinetic energy and speed 99.99999999999999999999951% of lightspeed (to quote The Other Wiki: "in a year-long race between light and the cosmic ray, the ray would fall behind only 46 nanometres") which in particle physics is simply unholy - energy equivalent to a baseball flying at 95 KPH. In a single subatomic particle. "Oh-My-God" indeed.
To date, the most distant GRB ever detected was 13.14 billion light-years away, making it not only the most distant GRB ever spotted, but also one of the most distant objects in the entire universe. Now that's what you call a Wave Motion Gun.
Roger Penrose theorised a particular kind of gravitational phenomenon... the "pp wave of death", a "gravitational plane wave exhibiting a strong nonscalar null curvature singularity, which propagates through an initially flat spacetime, progressively destroying the universe". A wave big enough to destroy the universe could never exist, but finite sized ones that could cause substantial damage might be created from certain kinds of black hole decay. These smaller waves were named "Thunderbolts".
Basically, the wave propagates at lightspeed so you'll never see it coming and spaghettifies everything it touches much in the manner of a black hole. From its point of origin, it could conceivably reach out to the cosmic horizon 30 billion lightyears away. The size of the wavefront would be limited, but whether that means it would only be capable of obliterating every solar system it reached or consuming entire galaxies is something for the theoritical physicists to discuss.
The A-10 Thunderbolt II carries the closest thing to a Wave Motion Gun that works right now - the GUA-8/A Avenger. Specifically, it's a 7 barreled rotary cannon that fires an INSANE amount of rounds (4200 per minute) and even appears to be a laser due to the amount of tracer rounds. The thing can cut a TANK in half and has a recoil as strong as the plane's engines. The plane is literally built around the gun.
Battleships from the Dreadnought era to the end of World War I had a reputation of being floating bringers of death, obviously because of their ridiculously large guns.
Subverted by the Yamato-class and Littorio-class of World War II: they had the firepower part right, being by far the most heavily armed warships of their theatres, but the Littorios tended to fire from too far without radars and never hit a target, and the one time the Yamato fired in anger, her guns were found to be too powerful, as the shell would punch right through the enemy ships and explode harmlessly in the sea.
To be fair, almost anything would punch straight through an escort destroyer when firing armor-piercing shells. Her heavy guns would no doubt have performed very well against heavy cruisers or other battleships.