Dominion Tank Police. Yes, you read that right. Tank. Police. They round up ordinary criminals, robbers, and thieves with tanks. And then coax confessions out of these same ordinary thugs with such methods as putting a grenade in their mouth, with a string tied to a ceiling beam, and balancing him on a chair with just 1cm of slack.
Appleseed has the Mobile Fortresses: Massive six-legged Spider Tanks the size of several building blocks. They have a BFG that is longer than it's own chasis length and dozens of multi-barreled auto cannons all over the places. Oh, and Olympus has 10 of them, protecting the city.
Subverted in one scene, where Deunan berates a police robot for putting down a criminal with a leaping double axehandle strike, saying the resulting smear on the floor was not going to go over well with reporters.
It's less prominent in Ghost in the Shell, but when the situation calls for it the Major is not above using automatic rifles with exploding bullets, and Batou shoots machine guns and even miniguns from the hip. When you want to kill cyborgs, your rule of thumb is the Chunky Salsa Rule. Their enemies frequently try to counter that with walking tanks.
Becomes a plot point when Togusa arrests a cyborg in the second season, after shooting him in all limbs to immobilize him. At the trial, the defense tries to say this was overkill on Togusa's part due to a prejudice against cyborgs, while Togusa counters that the cyborg in question had deactivated his pain receptors, so disabling all his limbs was just pragmatism.
For similar reasons in the Appleseed manga, the ESWAT team doesn't bother disabling cyborg guards or taking them captive and instead kill them outright. Not so much because of the lack of pain, but because they may have an internal radio and could silently call for help, compromising the entire operation.
Hentai Kamen, on occasion. Especially with any of the Shiki-s involved - although Shuto is slightly more balanced.
Eat-Man, what with all the BFGs. And in the Mira/Misha arc, Bolt is stabbed through the heart with a missile.
Blame! introduces the GravitationalBeam Emitter, a weapon that is incapable of anything less than overkill. The weapon is no larger than a pistol and the main character fires it off like farts after a bean casserole, despite it leaving a 40 kilometer long path of destruction along it's aim, no matter what happens to be in the way. And this being Blame!, it is not even most powerful among such weapons.
In 2199, the crew test fires the Wave Motion Gun on a floating continent to destroy the Gamilon base there, and accidentally end up destroying the entire continent. It should be noted that said continent was roughly the size of Australia.
When Grimmjow kills Luppi. Grimmjow first thrusts his arm through Luppi's chest, which would probably have meant that Luppi would have just bled to death if he let him, but then Grimmjow decides to go and blast off his upper body with a cero.
The Sokyoku used for the execution of serious criminals. Not only is it quite a spectacle - being a large phoenix - but it incinerates the target's soul, meaning they cannot be reincarnated into the living world.
Driscoll Berci is actually codenamed "The Overkill", and this reflects in his incredibly brutal fighting style. Naturally, Yamamoto treats him to the same principle by blowing him to ashes with Ryujin Jakka.
After Mello kidnaps TakadaMatt, in his escape attempt, is shot approximately fifty thousand times by a hugely unnecessary number of Takada's bodyguards. Many fangirls mourned. Clearly an egregious case of more dakka.
In the last episode when Light reveals he is Kira, and Matsuda shoots him several times. Subverted in the fact that Light isn't even killed by it, and only dies when Ryuk writes his name down.
2nd Gig has one of the best examples of this. After spending the best part of 26 episodes thinking he's bulletproof, the scheming Kazunoto Goda gets machine-gunned to death at point-blank range until his head asplodes by the Major and Batou.
There's also the terrorists plan to buy plutonium from the russian mafia to threaten the government with atomic bombs. The corrupt government takes no risks and calls a favor from the Americans, to nuke the entire refugee colony where the terrorists are hiding.
Lina Inverse is the queen of overkill. Having already fireballed and freeze arrowed an enemy, Lina often proceeds to finish them off with a DRAGON SLAVE!, which takes out the entire village with the foe.
Lina's blowing up of villages or large buildings tends to be a running gag, but the climax of Slayers Next plays this absolutely straight, when the God of the Slayers universe shows up in person to disintegrate and completely obliterate the Big Bad.
A sidenote to the spoiler; if cast wrongly, the spell summoning the above God could easily destroy the world they're in. Using that much destructive force against a single foe, even if said foe is a high ranking demon is indeed overkill.
Serial Experiments Lain has some guy trapped in an online game emptying an entire clip of virtual rounds on a very, very, very Creepy Child. It turns out the rounds were real, and so was the not-so-creepy child.
Black Scorpion in Samurai Deeper Kyo shoots out of his mouth a "beam" made of a thousand poisoned steel needles, each one being more than enough to kill a human in seconds.
Sousuke Sagara isn't usually given to overkill on actual battlefields, but - having been raised as a Child Soldier - when he's assigned as an undercover bodyguard to an Ordinary High-School Student, he applies good battlefield tactics to his school life and goes massively overboard. Some people say it with flowers; Sousuke says it with land mines.
A prime example is found in Super Robot Wars W, when asked to help Kaname find a way to keep delinquents from rival schools from crashing the school festival, he wires the yard with so many high explosives that when two Mechanical Beasts, monsters that usually give Mazinger Z a hard time, come stomping into the school, they're destroyed outright by the blast.
Giga Drill Breaker. Its various permutations only get stronger from there. Then there's the one-off Giga Drill Maximum, which involves attaching a Giga Drill to every point physically possible and shooting them out to wipe out enemies in all directions.
How do you hit an elusive target? You shoot every point in spacetime.
Super Tengen Toppa Giga Drill Breaker. There is nothing more. When the energy of the entire big bang, all that is and shall ever be is in Drill form, you know you may finally have enough daka.
Never! You can never have enough dakka. Not even when you have turned a weaponized Big Bang against the enemy.
Hellsing's Alucard will often use far more bullets and/or physical force than necessary to kill his opponents. Conversely, what seems like overkill from the other side is never enough to kill him.
Seras Victoria likes this trope as well. Lacking Alucard's capacity for physical force and regeneration, she dual-wields 30mm autocannons and uses them against human-sized targets.
In Samurai 7, some villagers get it in their heads to attack a thieving Humongous Mecha with farm tools. They get said mecha's BFS in response.
To make sure Frieza is finally dead after slicing him in half with his sword, Trunks proceeds to cut off his limbs and tail, chop his two halves into smaller pieces, and finishes it by incinerating his remains with a ki-blast. Given he survived a beating from Goku, getting cut in half, and being on an exploding planet, it probably seemed like a sensible precaution.
A subversion of the trope occurs during the Majin Buu arc. Gotenks has just blown Super Buu apart with several Kamikaze Ghosts. He and Piccolo then proceed to disintegrate the chunks of Buu's body (Piccolo saw Buu regenerate from getting blasted apart before, and wanted to take no chances). Why a subversion then? Because despite being disintegrated (i.e. his body was reduced to the atomic level), Majin Buu still manages to re-form his body. Buu then manages to reform himself from the SMOKE.
Right after Kid Buu is formed, his first act is to fire a deceptively-small ki blast with enough power packed in it to blow up Earth. When Goku and Vegeta knock it away into space, Kid Buu responds by laughing and then forming a massive energy ball strong enough to destroy the planet 10 times over. And this time, there's no stopping it.
Then Goku goes on to violate the laws of physics; conservation of matter when his Spirit Bomb kills Kid Buu with no chance of regeneration by destroying every atom he is made of. It's a trend too; Gohan took care of Cell in much the same way, except with a Kamehameha.
Wing Gundam's Buster Rifle. So powerful that it can blow up a colony or planetoid in one shot, and mobile suits often explode just from being near the beam. Heero usually uses it against small numbers of mobile suits. In The Movie, Tallgeese III has a similar weapon. The Wing Zero meanwhile has a Twin Buster Rifle, which is just as overpowered as it sounds.
The Mercurius and Vayeate mobile suits were deliberate overkill into the defense and offense departments, respectively. Mercurius was a test bed for the Defensor drones, three of which can form an energy shield that blocks most anything. Mercurius has eight of them. The Vayeate was basically a mobile suit-shaped engine for a gigantic beam cannon that might just outdo the Buster Rifle in terms of sheer firepower, and has a built-in generator so that it won't run out of power after three shots like the Buster Rifle does.
Muruta Azrael. First, when Azrael needs to defeat a ZAFT invasion of the Alaska base at Josh-A he stations a whole bunch of unwanted forces to defend the base, orders his fanatical subordinates to escape, then uses a Cyclops bomb to irradiate and then vaporize the base, its defenders, and the majority of the ZAFT assault forces. Later, when he is staging his final assault on the space fortress at Jachin Due, he not only deploys nukes at Boaz fortress, completely reducing it to ash, but he also deploys enough nukes against the Plant Colonies to wipe them out several times over.
His successor, Djibril, picks up the reins and does things more or less the same way. He tries to nuke the Plants right at the start of the war, uses the Destroy Gundam to crush local revolts in Eurasia, and fires Requiem at ZAFT in a last bid to kill them all.
ZAFT is little better. Before the series began, the Earth Alliance nuked one of the PLANT colonies, killing roughly 250,000 people. ZAFT's response was the deployment of N-Jammers on Earth, which triggered a catastrophic energy crisis in every nation on the planet. Late in the series when they completely disable the Alliance forces at Panama with EMPs, they don't secure the helpless and surrendering soldiers, they massacre all of them. The one ironic non-accomplice in this event is Yzak Joule, who feels that butchering unarmed and stationary targets is a waste of time, which is ironic considering his previous actions at Heliopolis and the 8th Fleet battle. At the end of the war, Patrick Zala's victory strategy involves purging all moderate factions in the governments including his old friend Siegel Clyne and then using the massive gamma ray laser GENESIS to scorch the surface of Earth, wiping out all life.
The icing on the cake is when you find out that both Azrael and Zala were being used by Rau LeCreuset in an attempt to bring about the extinction of mankind via Mutual Assured Destruction with both sides' superweapons (the nukes and GENESIS). What do you expect when the entire series is a Crapsack World that runs on Humans Kill Wantonly?
Also in Destiny, in a duel between Kira and Athrun, during a blade-lock, Kira cut off Athrun's Savior's arms, literally disarming it, and then proceeded to chop it into pieces in a rain of scrap metal, making sure that Gundam wasn't going to come back. It's a non-lethal example though since Kira is a Badass Pacifist and ... that's kinda his best friend he's fighting against.
Nice Holystone is like this with bombs. She stabbed a guy in the face with a knife then left a bomb full of fireworks attached to it. Later, she went to rescue her boyfriend who was in a garage with the door open. She blew a hole in the wall a little to the left and went in that way instead.
Louise Halevy had an over-the-top kill towards Nena Trinity, first she tore the Throne Drei limbs to limbs, leaving the cockpit with a bloody Nena, then shoves the Mobile Armor's arm into the cockpit, which impales Nena and cuts her in half, then the cockpit explodes. And wait a minute, there is still a haro left from this attack. Still not enough...
In the dub, which is actually surprisingly good, Tieria talks about this in episode 10. "So, I see you got caught. This just goes to prove that you never deserved to be a Gundam Meister. You deserve ten thousand deaths!" Ironically, moments later it is turned against himself. "So, I actually got caught. This just goes to prove that I never deserved to be a Gundam Meister. I deserve ten thousand deaths!".
Virtue, Nadleeh, and Seravee all qualify. Virtue is your average heavy-assault mecha with an incredibly destructive particle bazooka (Shown in one of the first episodes to not destroy the enemy, but break them down into particles). Nadleeh is slightly less bulky, and more mobile, but can dual-wield Virtue's shoulder mounted cannons as were they handguns. Seravee, well, it can wield 6 particle bazookas, each more powerful than Virtue's single bazooka. And if it is forced into melee combat, it can just wield 6 beam sabers instead. The movie went further and gave us the Gundam Zabanya, an upgraded version of the Gundam Dynames, and is more focused on precision, rather than fire-power, and yet it still has 20 Bits and 78 missile launchers built into its frame. And then there's the Gundam Harute, which in its own right is pretty all-round...until Hallelujah and Soma Peries awake, at which point it is controlled by the two most powerful Super Soldiers ever created.
Also from The Movie: the Gadelaza. Here is all you need to know about its overkill weaponry: 154 bits...and a Wave Motion Gun for good measure.
In Episode 31, the AGE-3 Fortress' most powerful attack involves combining the energy of all 4 of its BFGs into one huge blast, glassing a large part of the desert in its wake.
After War Gundam X: The X Gundam's and Double X Gundam's Satellite Cannons. Think of Wing Zero's overpowered Buster Rifle times about ten, and you might have one of these. Explicitly stated to be anti-army weapons or Space Colony destroyers.
Mobile Suit Gundam Unicorn: The Full Armor Unicorn. Basically they slapped a large backpack and extra boosters on the Unicorn and crammed in as many weapons as they possibly could. In addition to its standard armament of a Beam Magnum, head vulcans, and four beam sabers, it now has two double-barreled beam gatlings, another double gatlings on the shoulders, multiple missile pods on its legs and more on the backpack, two shoulder-mounted bazookas, two anti-ship missile launchers, two grenade launchers, 24 (MS-scale) hand grenades, and two beam javelins/halberds. This thing is seemingly designed to take on an entire army on its own.
In the Hidan and Kakuzu arc, Shikamaru uses this tactic to defeat the semi-immortal Hidan; first by blowing him up, then burying him in a deep hole.
Sasuke's Kirin, a temple-destroying bolt of lightning that can only be used once in a blue moon, but makes up for it in destructive power, which is used to kill one man named Itachi Uchiha. It even manages to obliterate Itachi's Susano'o and its so called invincible shield, the Yata Mirror, in the process.
When pushed to the wall, Deidara can summon all of his clay and use his "C4" attack, creating a massive clay golem in his image that scatters into countless microscopic bombs that, he claims, will dissolve any living being in range to dust. He created this technique in the desire to defeat Itachi, ironically the same person that Sasuke wants dead and the same person who inspired Sasuke to make Kirin, mentioned above.
Konan, the Patron Saint of this trope. For a battle she prepared six hundred billion explosive tags. Enough to fill a lake and explode continuously for ten minutes straight. And this was all to target a single man.
In Naruto Shippuden Movie 3, Naruto uses a massive (cough) Spirit Bomb (cough) Rasenshuriken to spike the movie's antagonist into the earth, and coincidentally, forms this attack in a manner very similar to the Spirit Bomb - gathering the energy of hundreds of smaller Rasengans.
The Tailed Beast Ball is a chakra blast that can destroy an entire mountain, but in the first few showings of the attack, the attack was used against a single (powerful) person. Later in the series, there have been massive Tailed Beast Balls; the most notable example is when Bee and Naruto both put all of their power into a Tailed Beast Ball large enough to engulf both of their beasts, in order to stop the transforming Gedo Mazou statue. The attack plowed through multiple mountain ranges, as well as the statue, and the resulting explosion engulfed an area 20+ times larger than one of the prominent battlefields.
The Juubi's attacks are on an even more massive scale. In fact, it formed a supermassive Tailed Beast Bomb, presumably large enough to destroy a small country, and fired at a weakened Naruto when it discovered that he had chakra from most of the tailed beasts.
Madara Uchiha loves this trope. When facing an army he summons a meteor and drops it on them, and when Onoki barely stops that he just drops another meteor on top of it. Then he battles five Kage-level ninja to their combined points of exhaustion, then summons 25 Wood Clones of himself who are near equal in power to the original and has them each summon a Nigh Invulnerable shield on top of that. However, he then averts this by upholding his vow not to use one of his most powerful jutsus twice in the same battle, feeling that it would be demeaning to the attack.
In the Sasuke retrival arc, Temari and Gaara revealing their new technique. Temari's Quick Beheading Dance is capable of leveling a forest. Gaara's Quicksand Waterfall Flow is a giant tsunami of sand that can change the landscape and it's usually followed by the Desert Imperial Funeral which crushes the victim.
Naruto and Sasuke's combined attack, Korin Shippū Shikkoku no Ya Zeroshiki, which combines a Futon: Cho Odama Rasenshuriken with Enton: Susano'o Kagutsuchi to form a gigantic firestorm of black flames. Even the Ten-Tails felt that attack!
It is famous for ramping up the characters to untold proportions where everything they do is essentially another shot on overkill...at least until the other person comes up with something that is EVEN MORE overkill.
During Alita's fight with Sachumudo, Sachumudo has nanomachine dust that breaks EVERYTHING apart making him nearly completely invincible...until Alita learns to use Plasma to burn it like gas only for Sachumudo to reveal that he can control magnetic fields and creates a giant ball of plasma that can incinerate Alita 100 times over...only for Alita to turn THAT over again by using her Hertza Haeon to blast the entire sphere into Sachumudo. And proceeds to tear the living crap out of him UNTIL HE REVERTS INTO AN INFANT FORM.
One moment is when Sechs enters the first tournament round against the Stellar nursery school where their first opponent Getz uses attacks that were used to take down WARSHIPS.
Anything involving Zekka automatically falls into this category.
Somewhat averted in Black Lagoon during the Hansel and Gretel arc. A group of bounty hunters guns down a car they believe is carrying the twins by not only shooting it with an RPG but also by riddling it with so many bullets that there is literally no part for the car without a bullet hole in it. But given that the twins hired two orphans to act as a decoy you have the overkill part just not the kill part, unless you count the two children in the car.
When Fabiola started a fight at the Yellow Flag, the Columbian cartel responded with a car-mounted machine gun hosing down the entire building. And they missed.
In the Gungrave anime Bear Walken's team is called the "Overkills." Which is demonstrated after they riddle Blood War with hundreds of bullets. Granted this is done after he is shot up by Brandon, Bunji and Harry.
Pretty much every major character applies this trope at least once. For example, Kaiba. Why blast your opponent with one large and powerful dragon when you can use THREE JOINED TOGETHER?
The end of the Yugi vs Kaiba duel in the Battle City Finals. Yugi could've simply used his Dark Paladin to kill one of Kaiba's three Blue-Eyes White Dragons, and would've won the match. Instead he paid a thousand lifepoints to allow the Paladin to attack and destroy all three dragons at once, and totally blowing Kaiba's ego to smithereens.
Epically done by Yami, after Yugi's soul is taken by the Oricalchos. Weevil Underwood taunts the guilt-wracked and now rather unstable Yami by tearing up a card in front of him after claiming Yugi's soul was in it and that tearing it up erased him, "as a joke". Yami...well, he goes totally and utterly apeshit. Using a spell card which allows him to attack as long as he continues to draw monster cards, Yami defeats Weevil by drawing two monster cards, which are enough to drop his lifepoints to zero. However, the enraged Yami then continues bashing at him, by drawing at least six more monster cards in a row, each hitting for 1500 points each. He would've kept going too, if Tea hadn't stopped him. Here's the scene...Not pretty.
Just to drive home how far into overkill this is: by the time Tea halted the onslaught, Weevil was down to -8300...dead three times over. Even at the card game's 8000 Life Point start rather than the anime's 4000, this whole onslaught would have been an One-Hit Kill.
From Season 4: "Mokuba, what do I always tell you? If at first you don't succeed, BLAST 'EM WITH YOUR BLUE-EYES AGAIN!"
Rebecca is defenseless with 100 life points left while Leon has two monsters, one with 400 ATK and the other with 3400 ATK. He chooses to attack her directly with the stronger one.
In the Season Finale of that season, Ryu duels Judai. In Ryu's final turn, he uses Power Bond to summon Cyber End Dragon, which doubles its Attack Points to 8,000, and then plays Limiter Removal to double it again, to 16,000. Ryu declares an attack against Judai's Shining Flare Wingman, which currently has 4,900 ATK, but Judai uses Battle Fusion, increasing his monster's ATK by that of Ryu's monster. (Meaning Shining Flare Wingman now has 20,900 ATK.) But wait! Ryu has a Battle Fusion too! Now Cyber End Dragon has 36,900 ATK! But Judai has one trick left: He uses a Trap called Final Fusion, which does damage to both players equal to the ATK of both monsters battling, meaning he and Ryu take 57,800 points of damage simultaneously and the duel ends in a draw. (By the way, at the start of the round, Judai had 100 Life Points remaining and Ryu had 550, and in this round alone, they both took more damage than fourteen times the Life Points they started with.)
An example that also doubles as a Crowning Moment Of Awesome takes place in Yu-Gi-Oh! 5Ds when Jack Atlas summons Red Nova Dragon for the first time. Both he and his opponent have 200 life points left, and Jack, after turning the Big Bad into a card purely with the power of his own hot-blooded awesomeness, proceeds to summon said card and steamroll his opponent for almost 2000 points of Battle Damage.
Jack (LP/700) and Scar-Red Nova (ATK/5500) later find themselves on the receiving end, courtesy of Jose's Meklord Emperor Grannel (ATK/12000). There's a reason its attack is called GRAND SLAUGHTER CANNON! There is also how Granel ruined Aporia's life 3 times; Childhood killing of his parents, killing his apparent lover, and being the cause of his death to Z-ONE.
In Yu-Gi-Oh! ZEXAL, Quattro uses his jumbo-sized shredder puppet to grind two monsters into submission, then "holographically" blasts their owners off the ground with the laser cannon coming out of it. He then tells them their suffering is not over yet, and proceeds to repeat the process by reviving the shredded monsters and grinding them over. But of course, how could he be done without some whipping?
In Yu-Gi-Oh! ARC-V, Yuya is wide open with 500 life points left while Michio has five monsters with 300 ATK each. He could simply attack with them all, but he chooses to pump one of them up to 4800 ATK at the cost of it being the only one allowed to attack. Ironically, this backfires because Yuya had a card that could stop one monster's attack, so had Michio chosen not to go for overkill, he would have won. Yuya then beats him in his next turn.
Well, luckily, they ended up not having to do that due to the excellent timing of Eva Unit-01 in going berserk again
There is very little left of Unit-02, and by extension Asuka by the time the Mass Production EVAS are through with them in End of Evangelion.
Essentially, Shinji does this in End of Evangelion and it's manga equivalent. At the end of it all, Shinji is left bitter, disillusioned and depressed. Problem: Your friends are gone. You're sure they left because you injured and killed your other friends, or let them die. There's nobody left who appreciates the sacrifices you've made or gives you thanks for what you've done, there's nobody to talk to and nobody understands what you've been through...because you failed them. Solution: Kill everyone.''Everyone''.
Rebuild 2.22; Asuka's introduction, the Dummy Plug activation against Bardiel, The fight against Zeruel and the last scene.
Yasuo Umetsu's Kite manages to top a lot. However, one sequence deserves special mention: After Sawa assassinates a particular target, one of the bodyguards she had dealt with earlier (by shooting him a bunch of times) tackles her out of the window of a multi-story skyscraper. She manages to turn it around so she's hiding next to his chest, making his wild retaliatory pistol shots useless, and the two of them fall and fall and land on a car on an elevated freeway...making the car fall through the freeway and land on a truck in the street, making that all through the street and into a subway station. As Sawa clings to the edge of the pit leading up to the normal street level, a falling electrical sign shaped like an arrow falls and crushes the bodyguard and causes the two vehicles to f***ing explode.
The Egrigori of Project ARMS are shown to have no problem offing large groups of witnesses and using their many government and police connections to hush it up. When two agents attempt to blow up a high school (simply because they themselves had been picked on in school), one points out that they could do whatever they liked and get it all passed off as a gas leak. One of the ARMS teens tells how, to get to him, the Egrigori blew up, burned down, and gunned his entire town (the same town was blown up, burned down, and gunned again when the protagonists return for answers). Later, the Red Caps basically cut off all possible escape routes from a town so the ARMS can't escape and holds the entire town hostage (thankfully it more or less turns out well). A flashback shows that Keith White had no problem having his soldiers machine gun a group of children. Oh, and the big climactic battle involved Black Alice seizing control of nuclear missiles and lobbing them at America while the Jabberwock goes on rampage, blowing everything up. Baked Apple indeed...
JoJo's Bizarre Adventure has two of the titular characters, Jotaro and Giorno, beating up Steely Dan and Cioccolotta for three and seven pages respectively, all the while shouting their beat-em-up phrases, and the cherry on top for Giorno is a WRYYYYY that continues off the page, reminding the readers who his father is.
Pretty much any super move is capable of obliterating an entire army of mooks. And yet they still keep coming.
Half-way through the first main story arc, Talpa orders his evil spirits to create a massive, organic bomb-like sphere of energy (called the matrix). Its purpose? To kill Rowan of Strata, who's asleep in space.
It started out with a cannon that levels a hundred houses in a row, had a bomb that could blow up a city, is now at island-destroying bombardments and according to Word of God, it's only halfway through the story.
And this isn't even mentioning the two ancient super-weapons we haven't seen yet, either of which apparently make the aforementioned island-destroying bombardments look like pea shooters by comparison.
A recent chapter explained there are actually three ancient super-weapons, Uranus, Pluton and Poseidon, and explained what exactly Poseidon is: a mermaid princess with the power to summon from nowhere and control Kaiju, whose power has been passed down the Mermaids royal line and is currently held by Shirahoshi. Note that for the entire arc where Shirahoshi appeared before being identified as Poseidon, people who knew her power openly admitted she could have easily destroyed the world by accident.
And then there's the Buster Call: a fleet of ten warships called in to destroy a single target, usually an island or a group of criminals. Each of these ships are HUGE, and carry about a thousand Marine soldiers each. The attack includes five Vice Admirals, the third highest marine rank. These ships will bomb their targets until there is nothing left, and can and will eradicate the population of entire islands. As this is the strongest attack the marines normally utilize against a target, the order for it can only be issued by ten people in the entire world (or persons given authority to do so by one of those people): the three Admirals (second highest Marine rank), the Fleet Admiral (highest Marine rank), the Commander-in-Chief (having authority over both the Marines and the several goverment agencies) and the five Gorosei (the leaders of the World Goverment). The readers are only aware of two times one has been ordered: the first to eradicate some archeologists who knew too much, and the second by accident of the incompetent CP9 leader Spandam pressing the wrong button (it is implied that the only reason he had this button at all because he stole it from Admiral Aokiji, who, knowing him, would've never given out something like that just to eradicate a small pirate crew).
This is AdmiralAkainu'smodus operandi. In fact, it's highly doubtful that the man knows the concept of overkill exists.
The main gun as shown in the episode Booby Trap. When the gun fires, it takes out everything in front of it, including part of a mountain range, carves a tangent through the ocean and blasts into space...all to take out a couple of scout ships, and giving the Zentraedi plenty of warning that the ship was active.
The large Wave Motion Gun implanted at one of the Earth's poles towards the middle of the series...that takes out a big percentage of the Zentraedi fleet of millions of ships in one shot. Too bad the Zentraedi had already bombarded the planet's surface to glass before the cannon could shoot.
The revolutionary who tries to lead Takashi out of the city gets caught by the police he shoots at them and they return fire with machine guns mortally wounding him, when he tells Takashi to leave the police proceed to blast the hell out of him with another fusillade, with one of the last hits splitting his skull in two.
In the AKIRA manga, the General at one point calls in an orbital strike on a mugger.
People are rarely killed in Pokémon. Enter Pokémon Hunter J, who is one of the few characters portrayed as being purely evil. So how do we dispose of her when karma catches up to her? Why, having her airship blasted by Future Sight, falling into a giant whirlpool in the middle of a lake. As the airship gets submerged, have the windows break causing hundreds if not thousands of pounds of water rush in to crush her. If that didn't kill her, the airship exploding will. Pokémon may not kill often, but damned if they don't know how to make sure you die.
And even then, Giovanni survived having his headquarters explode and collapse on top of him (in itself an example of the trope. We're talking a military complex of several stories here, after all) and he managed to haul himself out of the rubble, dust himself off, and walk away. After all, Meowth's dubious Imagine Spot scenes aren't the only reason Giovanni has become a Memetic Badass.
Mewtwo. As soon as he found out he was a clone, he killed all of his creators and blew up their lab. Notably, this is so far the only death in the dubbed version, as J's fate is left implied, but never stated.
In Maiden Rose, after forcing their way into the country via Taki's sacred family ground and killingnote nearly the soldiers sent to stop them, including Taki's lover, Berkut and co. expect Taki will have to give in to the intrusion, considering he is completely obstructed from acting by his higher-ups and shouldn't have even sent the force he did. Instead Taki orders his men to get the tanks ready, goes out and shoots armour-piercing, high explosive rounds (aka anti-tank weapons) at the oncoming passenger train. "That's insane" indeed, and also awesome.
Nearly every fight boils down to this when it comes to fighting the homunculi. In the manga, Mustang burns Lust well over a dozen times.
And then there is the battle at Briggs in the manga, where all of the Dracma army is destroyed in minutes.
Not to mention the Ishbal Massacre, where state alchemists were deployed to the front lines with Philosopher Stones to be used as human weapons. After deployment, the entire war was over in ONE DAY. Mustang is seen using alchemy to reduce an entire city to rubble with a single snap of his fingers.
Digimon Adventure: Myotismon has proven extremely hard to kill. They've destroyed him twice but he comes back in Digimon Adventure 02 for round three. So how do you finally kill this sadist off for good? Blow up his soul with the combined light of every Digivice on Earth fired from a BFG that shoots dark matter. To put this in perspective, just the light of eight Digivices completely negated an explosion that could completely destroy two dimmensions. Myotismon's soul got hit with the light of millions of Digivices in one, concentrated blast fired out of a darkmatter cannon. And this is one of those cases were the victim in question was just that hard to kill considering how they'd already vaporized him twice already and he keeps coming back. Since this particular Myotismon never comes back, it worked.
Digimon Xros Wars has Kiriha who lives by this trope, his tactics mostly involves his digimon unleashing a barrage of Beam Spam of ungodly proportions, if a single volley isn't enough, he keeps on firing some more, and he doesn't even care if Taiki's digimon get in his line of fire. In fact, he specifically invokes this when fighting regenerating undead opponents. How do you stop opponents that can recover from any attack you hit them with? You blast them until they can't.
How about the first time we see Skullgreymon. It slaps the other Greymon at a giant TV screen so it get's electrocuted and then just to be sure fires of a mini-nuke at it.
Puella Magi Madoka Magica: Akemi Homura lives and breathes this trope in every meaning of the word. At one point, she uses approximately $18 million in military hardware (including cruise missiles) to kill one witch, because it HAD to be dead. The kicker? She's supposed to be a 14 years old Magical Girl. Rambo, eat your heart out.
Although it should be noted that this was not overkill. The witch, rumored to be the most powerful one in existence in the series, actually survived.
Another overkill incident occurs to show just how close poor Sayaka is to crossing the Despair Event Horizon: after taking the head of the witch Elsa Maria, whose outline looks very much like Hitomi, her rival for Kyousuke's affections, she proceeds to chop into her with her sword again and again, laughing all the way. "It doesn't hurt at all!"
Fist of the North Star applies this to most battles Kenshiro participates in: by the time the fight's over, someone's gonna end up exploding into a pile of chunky salsa.
The organization GREMLIN wants to kill Touma Kamijou. They want to kill him so bad that they are willing to wipe out the human race just to be sure he's dead. They later cause a volcano to erupt, causing incredible destruction, just because they wanted to use the volcano's heat to forge a replica of Odin's spear Gungnir.
Make Accelerator angry and this is what he'll do to you. There wasn't even a drop of blood left of Amata Kihara when Accelerator was through with him.
There's Aleister Crowley being so obsessed with killing Shiage Hamazura that he calls in everybody from Academy City's Dark Side and then the military. The Girl in the Dress even thought Crowley was going overboard for spending so much to kill one guy. Despite what she thought, it actually wasn't enough because Shiage survived.
Gihren Zabi of Mobile Suit Gundam backs various superweapon projects, killed a billion people in the first week of the war with chemical weapons, drops a colony on Earth Federation headquarters, and uses nuclear weapons at the first real battle between Zeon and the Federation. That's without taking into account his use of the Solar Ray to assassinate one man; namely, his own father.
To say nothing of Char's slaying of Kycillia: Shooting her in the face with a Rocket Launcher.The missile was flying so fast it smashed through the bridge of her ship and tore her head off before it even exploded.
In the 5th episode of Sword Art Online, a man named Caynz is killed by being run-through with a sword and hung from a window with a noose around his neck. Subverted it was a ruse.
He actually shatters Erec's balls... quite literally.
From Gundam 0083, we have the Dendrobium "Orchis", a massive mobile armor which docks with the "Stamen", a regular-sized Gundam. It features self-guided Macross Missile Massacre-launching projectiles, chain mines, folded-up weapons for the Stamen to use, its own I-field generator, two massive claws outfitted with beam sabers, and a Wave Motion Gun, which can also be used to stab enemy mechs with, as seen in the climax. It's so powerful that in order to reconcile it with Zeta, they had to have the entire incident covered up.
In Jormungand, one of Koko's team member is killed by a CIA hit squad, three of whom make it out alive. She tracks them to a cave in Iraq, then calls in a B-52 airstrike on them strong enough to change the landscape.
In Rose of Versailles, Oscar dies when she is shot by over a dozen muskets. Justified, since that the inaccuracy of smoothbore muskets, that, unless you have very high aiming skills of a professional hunter, you had to resort to do this when you shoot a single person at that distance.