"Believing a giant human shaped robot is the best bet" only occurred after the first two episodes at least: based on the conversation with Gendo Ikari after expending their thinly-disguised nukes, their thought process was more towards "we've used all of our strongest options. Let's see your inferior robot do better". And Nerv showed them, yes, they can do better... and since, the army asked for Evangelion intervention with haste every other time an Angel appeared. ... "Eva 'em"?
The Macross series are an exception to the Nuclear Weapons Taboo, although its reaction weaponry isn't nuclear per se — it's an annihilation weapon, that is, an antimatter charge:
Macross 7: Lampshade hung in that, for all that it's implied that nuclear weapons are a weapon of last resort (Earth Command authorizing their use is seen as a big thing), every ship in the fleet seems to have unlimited stores of them. At one point, Basara even exclaims "Reaction weapons! Reaction Weapons! Any time something goes wrong, is that the only solution you have?!"
Macross 7 was probably given an unlimited supply of them because they did absolutely jack shit to the Protodeviln command ship.
The Robotech remix also features judicious use of nuclear weapons and their 'reaction' upgrades, here called 'reflex weapons'.
Happens in Getter Robo Go, after Shin Getter Robo goes berserk they various governments make several attempts to try and stop it, eventually resorting to a nuclear strike. The machine ends up grabbing the missile and combining with it
Bleach had Soi Fon,of all people pulling this as Bankai. Naturally, she didn't like its nature.
There's also the Kidou Cannon from the first movie.
In Code Geass, Britannia decides to go with nuking things as soon as they get them. They decide to give the first one to Suzaku, who really doesn't want to do it, but he ends up doing it anyway. Schneizel takes this to the logical conclusion of nuking every major city in the world to achieve world peace.
In Gundam SEED and Gundam SEED Destiny nuking ZAFT is Blue Cosmos leaders Muruta Azrael and Lord Djibril's first response. ZAFT creates devices like the Neutron Jammer and Neutron Stampeder to make sure that it can't happen again.
Nukes were also the first weapons deployed in the One Year War of the original Mobile Suit Gundam, by both Zeon and the Earth Federation. The Antarctic Treaty banning nukes (and biological/chemical weapons too) came about because before either side knew it, nearly half the human population had been wiped out in the space of a few weeks.
Subverted in Preacher. When the Saint of Killers obviously isn't falling to the forces of Starr's soldiers, Starr declares the battle lost and drops a nuke, wiping out the rest of his troops. Then the Saint emerges from the blast site. His only words? "Not enough gun."
In Atomic Robo this is the hero's response to a giant moving pyramid headed toward Luxor.
Robo: I didn't found this crazy organization to not nuke things.
In The Secret History, the nuke dropped on Nagasaki was really just to kill William de Lecce. It's a matter of speculation whether he's really dead or not.
The Cultists of Dagon use underwater nukes against attacking NEG forces in Aeon Natum Engel. Radical measures were proposed in both NEG Military High Command and the Migou Council, but calmer heads prevailed.
The nBSG Cylons try to nuke the Stiletto in The Open Door, but the ship tanks all of them without needing its shields.
In Shinji and Warhammer 40K, when Gendo asks Kaji how many UN warheads, dirty (nuclear) bombs or otherwise, are pointed at Tokyo-3 in case Misato and Risuko's plan against Iruel fails, Kaji's reply...namely, all of them, meets with his satisfaction.
The Grand Empire somewhat does this to Madara and his Zetsu's. But it is implied that they first had someone check to see what the impact of the fallout would be. Their plan for the effects of the fallout makes it this trope.
In Project Tatterdemalion, the top authorities involved initially wanted to nuke the facility after the Hollows began rampaging. Bad idea. As Juushirou explains, heat and radiation kill a lot of things, but only if they're contained long enough. If the Hollow virus was sporific, all nuking the facility would've done is pop open the box the Hollows were kept in, and spread still-infectious Hollow bits up into the jetstream, dooming the world...and infecting the spaceports. And as Juushirou said, all they knew for certain was 'Alien,' and 'Dangerous,' so it could've indeed been sporific, or close enough for an apocalypse.
In the Deva Series the Americans use a pair of SLBMs to obliterate a massive swarm of Seeds that were heading for either New York or London. Even though nothing else significant was harmed - middle of the ocean, and all - Hayate was not happy, since she feels that it wouldn't be too much of a stretch now for someone to think to launch a barrage of nukes at Al Hanthis... which would obliterate Cairo in the process. Also, the Al Hantheans are utterly horrified once they learn exactly how nuclear weapons work. It is probably worth noting that there is In-Universe debate as to whether this was Nuke 'em or Nuclear Option; it did work, and Yussef and Maunders don't consider it an overreaction. Yussef notes that point defences now make anything short of a nuclear Macross Missile Massacre worthless against Al Hanthis and would rather not use another if possible, but is mentally prepared to do so if all the chips are down, unlike Hayate who absolutely refuses to consider it.
An End To All Things: Someone nukes the town in the opening act, according to Okazaki's memories. Or will nuke the town, the story has a measure of Anachronic Order with regards to that event.
Most 1950s B-grade SF movies. Whether it works or not varies between films.
When asked how to deal with the Xenomorph threat in Aliens, Ellen Ripley responds with the famous line "I say we take off and nuke the site from orbit. It's the only way to be sure." In hope of a different answer the Corrupt Corporate Executive asks Corporal Hicks for his advice and he repeats the same thing. Of course, Ripley turns out to have been right in this case, and anyway there was only one uninfected person left alive in the colony. The line is frequently acknowledged in other mediums.
The above quote is referenced in one of the Narbonic strips linked here.
After being made aware of the aliens' plan to exterminate the human race and strip Earth of all its resources by means of a telepathic vision, a furiously badass President Whitmore in Independence Day gives the order to "Nuke 'em. Let's nuke the bastards." Subsequently, a U.S. stealth bomber attacks the alien spaceship over Houston, Texas with a nuclear weapon, which predictably, has no effect on the spacecraft whatsoever. See also: Hope Spot
Extended in Evolution, but it uses napalm. The army gets napalm to destroy a lifeform, just after the protagonist discovers a smaller sample expands by many times after being touched by fire. They tell the army, they attack anyway and the monster becomes about a million times bigger.
The scientists were unable to pass on their specific information because the general in charge was an asshole who refused to take their call.
Subverted in Mars Attacks!!: Nothing Earth has done thus far can so much as scratch the Martians. The General Ripper has spent the movie insisting on using nuclear weapons, and the President, depressed at how nothing is working, finally gives the go-ahead. The Martian response to a nuke headed their way is... a small flying nozzle which intercepts the missile and sucks up the explosion. The Martian leader inhales the explosive gas and speaks with a squeaky voice, as though the gas were helium. It's possible that this was a subtle joke: when you fuse hydrogen (as in a hydrogen/fusion bomb), you get helium.
Subverted too in the 1953 version of The War Of The Worlds. The military throws everything against the Martians before reluctantly turning to a nuke as a last resort. Notably the civilian scientist hero does not, unlike his counterpart in Independence Day, object to the use of nukes. The nuke fails to do anything to the Martians.
Unlike the original H.G. Wells novel, in which the Martians are vulnerable to Earthly weapons, but theirs are so much more powerful that resistance is futile once the element of surprise is lost.
Variation-In the 1991 film Godzilla VS King Ghidorah, present-day Japan decides to nuke the Godzillasaurus that would've become Godzilla (who is now at the bottom of the Bering Sea) so that he can fight King Ghidorah. Subverted in that, he's already been nuked/mutated...in a sense (by absorbing the radiation from all the sunken nuclear subs already present in the area) and nuking him...again...only makes him bigger and far more powerful than before.
In King Kong Vs. Godzilla the military actually seriously considers nuking Kong. Luckily the heroes manage to find an alternative. Although, this proposal only appears in the English version.
It should be noted that Godzilla can (and has) die from too much radiation (as seen in the film Godzilla VS Destroyah). The only problem is that doing so causes him to go into a nuclear meltdown which would result in destroying all life on earth and reducing the earth to a wasteland. Unless you have an adolescent Godzilla (IE: Junior) around to absorb the radiation and reach his adult form.
Alien vs. Predator: Requiem.The "Predalien" has already managed to overrun the entire town with its more classically-styled offspring. The military solution, after the recon unit sent in is quickly butchered? Nuke the town and tell those still alive to congregate in the center of the town for an airlift, so as to keep the aliens from spreading out.Harsh, but completely justified under the circumstances.
The Abyss. While suffering from paranoia, Coffey decides to destroy the aliens by sending down an armed nuclear warhead.
Return of the Living Dead. They nuke the zombies (and all the main characters in the process), but, of course, that just causes the zombification juice to re-enter the atmosphere and create more zombies. Good going, dumbasses.
In the Sci-Fi channel movie Baal Lord of Storms, the military considers nuking a storm front. While it's clearly the wrong option, there's a techno-babble reason given (something to do with disrupting electro-magnetic waves) to make it merely a bad idea and not simply a completely cracked out of their mind idea.
In the original Stargate movie, Colonel O'Neil secretly brings a nuke through the Stargate with the team on its very first exploration mission. His orders? Nuke the place if there's any sign of hostiles. They end up using the nuke to kill Ra.
In The Avengers, the WorldSecurityCouncil decides that the Avengers are going to lose the final battle and decide to just nuke Manhattan Island (along with all its inhabitants) to disrupt the wormhole through which the Chitauri army is invading. Tony winds up nearly sacrificing himself to guide the nuke into space and chuck it at the alien ship instead. Needless to say, neither Nick Fury nor any of the Avengers were particularly impressed by their stellar display of competence.
Subverted in the book and the 1971 film version of The Andromeda Strain. The titular extraterrestrial organism (a single-celled, quasi-crystalline life form) mutates as it's exposed to ionizing radiation - at a rather sedate rate under atmospheric UV exposure, extremely rapidly with more powerful sources. Of course, the secure biohazard laboratory where this bug is being studied is equipped with a thermonuclear device for "terminal sterilization" in case of contamination, and the lab becomes contaminated when the organism mutates to a form that degrades organic polymers, thus compromising the synthetic rubber gaskets and hatch seals throughout the lab. Failsafe Failure ensues.
In Day by Day Armageddon, the US Government decides to nuke most of the major US cities due to the spread of zombies getting out of hand. Unfortunately, this doesn't fix things, because the zombies who weren't caught in the nuke blasts absorbed the radiation and it somehow turned them from slow zombies into fast zombies. Obviously, these people have not read The Zombie Survival Guide, which specifically argues against this (for pretty much this very same reason).
Live Action TV
Babylon 5: This show gives us John Sheridan, who uses nuclear weapons no less than four times against seemingly unbeatable opponents and winning all four times. In the commentary track for 'Thirdspace', Bruce Boxleitner even calls him "John 'Nuke 'Em' Sheridan", all but making it official.
Battlestar Galactica (Reimagined): The new series gleefully hurls nukes around with wild abandon. In the mini-series alone the Twelve Colonies are hit by thousands of nukes: Helo reports seeing six mushroom clouds just from the one area his Raptor has landed in on Caprica in the space of about an hour. Galactica itself withstands a direct hit from a nuclear missile, although it sustains heavy damage and more than 80 casualties. Pegasus was also nuked a couple of times while in dock during this time. Nukes are also later used to destroy a Cylon basestar and Gaius Baltar appropriates one, allegedly for his research but this is later used to blow up at least three of the refugee ships and kill more than 3,000 civilians. The high-point for the use of nukes is when Pegasus withstands no less than three nuclear hits at pointblank range and shrugs them off to inflict grievous damage on the attacking Cylon basestars with its guns. Nukes are later used to destroy the Cylon Resurrection Hub and in the stand-off between Galactica and the rebel basestar. In a moment of possible high irony, the Galactica finally reaches Earth (the first one) to find the planet irradiated by a nuclear war, which has left the planet uninhabitable. Finally, the Colonial Fleet uses all of its remaining nukes to destroy the Cylon Colony Ship (and most all of the Cylons) in the Grand Finale.
Farscape: Does this twice, once in the first season in order to destroy Scorpius' Gammack Base (Though it isn't technically a nuke per se, the yield is similar), and again in the last season, where John creates a makeshift nuke to use as leverage in his plan.
MacGyver: In the pilot, the army plans to use a nuclear warhead to stop a chemical leak. In the end, Mac fixes it with chocolate.
The Outer Limits (new version): This show likes to nuke them. In "The Light Brigade" the titular human warship is hit by two nukes. In "Trial by Fire" the US president tries to nuke the aliens who have splashed down in Earth's oceans.
Revolution: After allying with Randall and gaining a permanent source of power, Monroe manages to build a nuclear bomb and attempts to use it to destroy Atlanta and cripple the Georgia Federation. Fortunately, the protagonists stop this just in time.
Stargate SG-1: This show will sometimes resort to this, with early seasons favoring the Five Rounds Rapid treatment of nukes (namely epic failure) to give the title object and title team justification for existence. There is one early case where a nuke is actually used to prevent them all from being sucked into a black hole.
Later seasons started using them more frequently, such as the Mark IX "Gatebuster," a naquadriah-enhanced warhead with a supposed yield of several gigatonsnote For reference, the most powerful nuke ever actually detonated in reality was "merely" 50 megatons, which is roughly 100 times weaker than the Gatebuster. Of course, given that they were fighting the Ori in their last season, it's logical that they would bring their most powerful weapons to bear.
The Spin-OffStargate Atlantis, on the other hand, practically giggles any time nukes are mentioned to the point where John Sheppard makes putting a nuke on the enemy ship his default anti-capital ship tactic, though he's more often than not justified in this, and pretty much every application works as intended. Nukes are used on the first two Hive Ships sent to Atlantis, one flown into the Dart Bay, the other beamed on. Nukes are beamed onto two more Hive Ships. The Genii use one to kill one of their own armies and their boss in a coup. Finally, Sheppard single-handedly flies an F-302 into the Dart Bay of a Super Hive Ship undetected and armed with a nuke.
Then there's the giant Horizon planetary attack missile launched against the Asuran homeworld, which carried six Mark IX warheads.
Randy Newman's "Political Science" (incorrectly known as "Let's Drop the Big One Now") deconstructs and mocks this trope by suggesting the flimsiest, most frivolous excuses for nuking everyone and everything (except Australia).
Tom Lehrer wrote the famous hit "Who's Next?" about the number of countries getting nukes. Especially funny and biting because this was in 1950, so the effects are well remembered.
Used intermittently in Warhammer 40000. Actual nuclear weapons are not prominent, being relegated to use by garrison forces for the most part. When a cosmic horror rears its head the three most favoured options are saturationorbital bombardment, Exterminatus or deploying the Grey Knights.
Weapons on the same or greater scale as nuclear weapons include: plasma torpedoes (200 meter inter-ship ordinance), engineered viruses (including the Worldkiller Virus,) Vortex weapons, and Cyclonic torpedoes (which burrow into a planet's crust and detonate in the mantle, causing widespread surface devastation.)
When it looks like a Space Marine force isn't going to be able to protect or take back a planet, it is their responsibility to blow the planet up before they leave.
In Shadowrun, Ares Macrotechnology used a tactical nuke in an attempt to saturate Chicago's astral plane with toxicity and kill the hordes of bug spirits that ravaged the city. Fortunately the bug spirits' own energy-shield trapped the physical and metaphysical blast inside the bugs' nest, preventing its full impact from reducing Chicago to a radioactive ruin.
You gotta give props to FASA: it takes nerve to nuke your game company's own hometown.
Their own headquarters, as a matter of fact.
In the Old World of Darkness, this was the Technocracy's answer to the Ravnos Antediluvian rising. Well, OK, it was repeated applications of Prime-enhanced spirit-shredding nuclear warheads, mixed in with the three most powerful Kuei Jin alive throwing down on Ravnos for several days while underneath a hurricane created by their powers to block out the sunlight, and then when the Kuei finally went down that cleared the way for the Technocracy to focus the power of the sun on Ravnos five times over by using multiple redundant orbital solar mirrors, at which point — already completely exhausted of blood by his three-day kung fu vampire throwdown and having been repeatedly nuked in both his immaterial and his material body — Ravnos finally turned to ash and died.
Averted in GDW's cold war tactical games like Harpoon and Air Strike which focused on conventional weapons. For a nuclear variant the game designers recommended dousing the game in lighter fluid and setting it on fire.
Mekton has rules for nuclear weapons, with the degree to which you are screwed being directly proportional to how close you are to the centre of the blast. If you're within the basic blast radius, you automatically die unless you have a really good excuse. Outside of that, you're simply very likely to die. It also gives some key rules about using them so as not to destroy the game, just the battlefield, such as "Only drop them to establish a scenario, rather than as a cheap Draw button" and "if you must drop it during the fight, do so in the centre of the battlefield." (Just to reinforce this, the "nuclear" upgrade for missiles and bullets is very expensive.) Supernovas use the same rules, although the rules state that you just treat the hex you're in as ground zero and quit whining - the entire system is screwed, why should you be immune unless you're flying an Excessive Scale Humongous Mecha that could stomp Cthulhu underfoot?
In Eclipse Phase many nations resorted to nukes, orbital kinetic strikes, and antimatter bombs to try and halt the TITANS during the Fall. The end result was the death of 90% of humanity and a mass exodus from earth. Not an uncommon modus operandi for Firewall either.
In Crysis, after pulling off the island, the Navy decides to nuke the aliens, deflecting Dr. Rosenthal warnings that they absorb energy with comments along the lines of "There's no time to study them." To nobody's surprise, the aliens absorb the blast and get stronger. Just as predictably, it's all your problem from there. And then played straight by having the player use a nuclear grenade launcher on the alien space ship.
In World in Conflict, this happens twice in the campaign. First a tactical nuke is called in to take out an overwhelming Soviet force headed for a "hold at all costs" level objective. Then, at the end of the campaign, you are racing against time to push the Russians out of Seattle before their Chinese reinforcements arrive and the president is forced to obliterate the city. And you can call in as many as you want in multiplayer.
In Renegade he decides to nuke a small town just to eliminate the protagonist and his squad. Justified in that he just killed his way through a mansion filled with Nod's elite.
In Tiberian Sun Kane, dissatisfied with General Vega (an Eye Candy addict), decides to reprimand him. With a tactical nuke. Sadly, he misses Commander McNeil by a few minutes.
In ancient history, in Tiberian Dawn you get nuked by Kane during the final mission. He sure likes his nukes.
In Red Alert 1 Stalin launches nukes against capital cities of the Allies to ensure victory. Of course, the good guys disarm them in flight.
In Red Alert 2 Chicago is destroyed by a nuclear bomb after the player destroys the psychic amplifier and the USSR has no further use for the city. A technical Fission Mailed too.
In Red Alert 2: Yuri's Revenge the mission Power Play basically revolves around you trying to stop Yuri from nuking the city every ten minutes. It doesn't help that Yuri tends to use his first nuke to destroy your War Factory and you don't have a Construction Yard in this mission.
In Red Alert 3, Soviet General Krukov and Premier Cherdenko go back in time and kill Einstein to prevent him from granting the Allies technological superiority. On their return, they find that Japan has become the Empire of the Rising Sun and is invading Leningrad. Krukov orders the entire Soviet nuclear arsenal to be used in defense of Leningrad. Nuclear what now? Oops.
In Generals the Chinese have nukes. And you can build as many silos as you want. Each with a separate nuclear silo. You don't need line of sight to fire them either. Death from Above indeed.
The iconic Black Mesa Research Facility is destroyed by a nuclear blast at the end of the Half-Life expansion, Opposing Force. Curiously you spend a large chunk of the game trying to avert this, but a few minutes after succeeding you see the G-Man reactivating the bomb from afar. Obviously you survive, as do a number of other characters who go on to appear in Half-Life 2.
The Omega Cannon in Hunters is practically a portiable nuclear bomb. It's the only weapon that can kill the final boss and in multiplayer, it kills anyone, including the shooter, instantly if they are caught in the blast.
In DEFCON your job is to pretty much nuke the entire world (with the exception of your own continent). While several other weapons beside nukes exist, they are mostly used to shoot down nuclear missiles. Or shoot down airplanes carrying nuclear missiles. Or sink submarines that can sneak up on you and fire nuclear missiles. And all is shown in the style of the final scene from WarGames.
Operation Flashpoint and its successor Armed Assault and Arm A 2 all feature nukes to some extent - though in keeping with the ultra-realistic tone of the games they are only used as a last resort by madmen. And their detonation, should you fail to stop them, is shown to kick off global thermonuclear armageddon. Particularly true in Arm A 2 bonus mission 'Eagle Wing', which starts off with your AH-64D moving ahead of a naval taskforce to engage Russian forces, but goes all to hell... A panicked "Pull Back!" message from command is cut short by a nuclear detonation, and your helicopter is smashed out of the air. You then have to escape and evade in a silent, devastated world (and this is well outside the blast radius, which covers most of the 100km^2 map!) with your character clearly panicking as an enormous mushroom cloud towers over the horizon and black ash falls from the sky. Incredibly well done.
Every game in the main Civilization series features the development of nuclear weapons (or "Planet Busters" in Sid Meier's Alpha Centauri) in the late game, which are by far the most devastating offensive units available even after it becomes possible to build countermeasures. However, using them makes all AI players declare war on you automatically, releases vast amounts of pollution, and in some games advances the Global Warming timer by a significant amount. Too bad the AI doesn't have nearly the same compunctions about deploying them.
In M.U.G.E.N: The A-Bomb. It nukes your characters and completely vaporises anything that isn't as overpowered.
Global Effect (an early 90's PC game) would let you nuke enemy cities at will. Made the whole screen fade into white for a few moments. It was a guaranteed way to punch an ozone hole in the sky.
The Carronade or Hex Cannon in Breath of Fire IV is depicted as a particularly (and literally) nightmare-inducing magical thermonuclear weapon equivalent. The really scary thing is in the power source and in the ammo; the power source is a princess who is converted into an artificial Endless so that she can be perpetually tortured, whilst the ammo consists of people with a close connection to the target being literally tortured to the point of a mental breakdown and then subjected to human sacrifice. It's the pain, rage, and suffering that ends up being the "warhead".
Depicted originally as a plot-point in a town that was Hex Nuked, including literal Hex Decontamination Teams. Even with this, it is stated will take many years for the hexed city to recover—which has had to be evacuated of residents.
Depicted most tragically in Fou-lu's storyline*
Peasant girl meets dragon-god. Peasant girl falls in love with dragon-god. Peasant girl is taken prisoner by empire dragon-god founded 600 years ago, tortured horribly, and ultimately used as Tactical Thermonuclear Peasant in attempt to kill dragon-god. Dragon-god survives (barely) and goes completely bugfuck nuts
when he realises who was used as the ammo. Suffice it to say that it does not end well for the Evil Empire.
In Prototype, Operation: Firebreak, which is nuking the area, is the Final Solution to deal with a virus infecting a town.
The first major arc of Shin Megami Tensei I ends with the Americans dropping nuclear missiles on Tokyo. You later Time Skip 30 years into the future, and not surprisingly, the rest of the world has been reduced to nuclear ruin.
BlazBlue reveals that Kokonoe keeps a fully-loaded silo in range of her lab just in case she needs a quick solution to Yuuki Terumi or whatever he may be cooking up this week. Hakumen (who saw a nuke strike against the Black Beast do jack-shit to it) is understandably horrified when he finds out.
One of Axton's skills in Borderlands 2 lets him set off a mini-nuke when deploying his SABRE turret(with its own cooldown).
In the X-Universe series, Hammerhead Missiles are nuclear-tipped Terran missiles. A single Hammerhead is more than capable of wiping out an entire fighter wing or destroying a corvette with one shot. Pirates love to fire these things off in mass. In X3: Reunion, the missiles are simply labeled as "Unknown Object" until the Terrans show up.
Near the end of Resident Evil 3 Nemesis, the United States government concludes that Raccoon City cannot be saved. In order to avert wide-scale pandemics of the zombie plague, they fire a nuclear missile. As the news report at the end puts it, "Raccoon City has been literally wiped off the map."
Parodied during the "That Which Redeems" arc of Sluggy Freelance, where the nuke dropped on the demon army turns out to be an acronym for "'Notification of Unified Kindness' Envelopes." Instead of vaporizing everything for miles around, the "nuke" blankets the area with thousands of polite yet stern letters asking the demons to please stop their invasion. This is still considered an abominable act by most Dimension of Lame residents due to the collateral damange:
Alt-Gwynn: "Terrible thunder. Paper cuts impending. Litter unimaginable."
In The Salvation War noted several times where Nukes might of been useful, and Word Of God said that if the legions of Hell were NOT in a place where quick military action was able to take place they would of Nuked them. It wasn't needed in the first book just because of the effectiveness of modern military hardware. The second book however has three Nukes, and one of them plays this trope straight in a sideways way. One was launched by a Nuclear sub being controlled by an angel, and another was used to wipe out an angel army. The third almost killed Michel, who sensed the cart he was puling was a bit to heavy, and kicked it back through a portal.
Megas XLR is apparently armed with nuclear weapons. In the "Viva Las Megas" episode, Coop proposes using them to blast out of an underground bunker, but is waved off by Jamie and Kiva. He laments "What's the point of havin' nukes if I can't use em?"
In ReBoot, standard Guardian protocol for dealing with a Class 5 web-creature in a system like Mainframe is to destroy the entire system. A Class 5 creature is capable of opening a portal to the Web, and through Mainframe's connections that can lead to an invasion of the entire Net. The Guardians themselves dislike this policy, but the Web and the creatures within it are seen as so great a threat that even the loss of an entire system is preferable to a war. They do at least send operatives to the systems in question to positively confirm that there is such a web-creature present, even they would not blow up a city on an unconfirmed rumor, but once the rumor is confirmed they push the button without a second thought.
The Iron Giant has a sequence where paranoid intelligence agent Kent Mansley prompts a nuclear strike on the Giant because he wanted to see the Giant destroyed, rashly ordering it by grabbing the radio from the General that was about to have them stand down, as the situation was over. The General then asks "WHERE'S THE GIANT, MANSLEY?!" Which is about 50 feet from him.
In Justice League Unlimited, General Wade Eiling'sfirst thought after he is told to fix the Doomsday situation is to drop a nuclear warhead (with a little kryptonite mixed in) on Doomsday and, by extension, Superman and San Baquero. Since Eiling planned to get to Superman eventually and had long wanted to stop drug smggling from San Baquero, he considered it killing three birds with one stone.