Zero Effort Boss

"There were sequences really near the beginning that kicked my ass until I was wearing my buttocks like a hat while the closest thing to a final boss fight is basically you versus a wheelchair bound cross-eyed hobbit and you’re armed with the BFG 9000."

- Ben "Yahtzee" Croshaw, on Halo 3.

An Anticlimax Boss is easier than the plot implies, usually easier than all the other bosses you've fought until this point. A Zero Effort Boss is easier to fight than the crates you destroyed for ammo. This is the ultimate intentional expression of an Anti-Climax Boss, a boss who is literally not a challenge at all. Best case scenario, you actively have to try in order to lose. At its worst, you are incapable of losing even if you try.

The most common version is The Man Behind the Curtain variety. You have slaughtered the Big Bad's Mooks, infiltrated his Evil Tower of Ominousness, battled through his Elite Guard, and barely survived the fight against his Dragon. All that's left is the weak, unarmed, defenseless mastermind behind it all. A subversion of Authority Equals Asskicking, usually The Dragon was intended to be the real Final Boss, and this one-shot kill is meant to provide closure to the story. Or maybe it's just Played for Laughs that the Dark Lord Bludentiers is a fat slob who can barely lift a sword. Sometimes, there is an actual battle, but it's effectively won on the penultimate hit, requiring the player to finish off a vastly weakened enemy.

A less common variety is that for some reason, perhaps Eleventh-Hour Superpower, you are invincible for the final battle. This invincibility may not be obvious at first, since you still suffer damage and get attacked, and only reveal itself when you lose all health. Either way, it is impossible to lose.

Subtrope to Anticlimax Boss. Also see Breather Boss. Not to be confused with a Cutscene Boss, which is not only Zero Effort, but Zero Interactivity. It doesn't count if you spent 10 hours Level Grinding to kill the boss in one hit, that's not zero effort.

Contrast Hopeless Boss Fight, which relates to boss battles you cannot win for the sake of the plot.

Action

 * Cannon Fodder 2 features what may be one of the earliest examples; after blasting your way through dozens of nigh-on-impossible battles, your last mission is to assassinate a general. Your squad appears on a tiny map, positioned practically right next to him. He's unarmed. You're not. Bang.
 * According to Stoo Campbell's Web site, this was meant to represent a firing squad.
 * When you encounter Mysterio in a store in Spider-Man 2, the intense battle music begins, his life bar, which is much, much bigger than any of the games other boss', appears on-screen, and it appears that you're in for one hell of a fight... until you realize that his only "attack" is yelling increasingly desperate (and ultimately, ineffectual) threats at you, and that his whole life bar is completely drained with a single punch. It's obviously a joke, and fits with the character's status as a Master of Illusion. View the epic battle here.
 * It also embodies his Villain Decay, since when he first popped up he was attacking the city with robot drones and attempting to steal the Statue of Liberty, but when you run into him for the final battle he's holding up a convenience store.
 * It gets funnier. Turns out that you can actually ignore Mysterio and then calmly walk past him out of the store and then walk down the street. The whole time you do this you can here Mysterio in the background yelling at you making threats and trying to make it seem like he scared you off. Walk back into the store to clock him in the face and see how quickly you can crush any remaining self esteem Mysterio might have.
 * Operation C ends its final stage with a combat cyborg, followed by a hallway with a trio of timed deathraps, leading up to... an alien cell in a giant jar. You can still die, there's a bottomless pit in front of you, but the cell itself has no form of defense.
 * Gungrave, after beating the last boss you are left only with the game's Big Bad... who just stands there and lets you shoot him. It'd be a cutscene boss except the game does force you to press x to kill him, and if you refuse to press anything then you just stand there with your gun trained on him forever.
 * In Bloody Wolf, there is a boss who only fights with a knife. The first time you fight him, you are also restricted to using your knife for non-specified reasons, making him a possible threat. The second time, you can use your gun, which kills him with one hit.

Action Adventure

 * The final bosses in Legacy of Kain: Soul Reaver 2 would normally be pretty challenging, if not for the bit where you're, y'know, impossible to kill...
 * Metroid: Other M has, the cybernetic reincarnation of  , is incredibly easy to beat despite being built up to be quite threatening. Some players kill her by accident.
 * That said, some other players won't notice her at all and be slowly hacked to death by the that you are desperately fending off.
 * Near the end of Star Fox Adventures, you finally face off one-on-one against Big Bad General Scales. As soon as you draw your weapon, the battle gets interrupted by a cutscene where Scales is unceremoniously offed and the game is Hijacked by Andross for the finale.
 * in the Evil ending of In Famous 2. It's justified as he understands that he stands no chance against Cole but believes that he still has to try to It's more a Last Stand than anything.
 * James Bond 007 for the Game Boy has this. One mid-game boss is a big, burly man that the game has hyped up as being a major threat. However, he's actually a wimp; he gives up after one hit from any weapon and starts crying.
 * Madame Clairvoya from Luigi's Mansion. While she is considered a Portrait Ghost, she's no threat to Luigi, and after he brings her Mario's hat, shoe, glove, letter, and star, she surrenders, feeling her portrait is safer with Bowser potentially loose. Downplayed a little, as using the Poltergust on her might create a Poison Mushroom (a problem with all Portrait Ghosts) but the only danger there is that it might prevent you from getting Clairvoya's Gold Frame.

Beat'Em Up

 * The so-called "final boss" in The Incredible Hulk for the Super NES is the Leader, one of the Hulk's deadliest foes in the comics, thanks to his tremendous intellect... but in the game, all he does is stand in one place and laugh, and one punch is enough to defeat him, sending him tumbling down a Bottomless Pit. You have to uppercut him though, he laughs at standing punches for some reason.
 * See it here.
 * Having slashed your way through Bangler's entire military in The Ninja Warriors, you corner Bangler himself in a dead end in the capitol building. He cowers, hyperventilating, against the wall, and takes a single unopposed slash to kill. However, you do have to walk across the entire width of the screen to do this, as for some reason he's completely immune to your shurikens.
 * If you take too long to kill him, he will take out a gun to shoot you. But you have to be trying in order for him to do so.
 * Obscure ZX Spectrum game Oriental Hero is so impossibly difficult that the only way to even reach the final boss is cheating. The final boss himself on the other hand… well, look for yourself.
 * In Marvel Comics, Mr. Sinister is one of the nastiest, most evil, most brutal foes the X-Men have ever faced. Not the case, however, in the Deadpool video game, where he's the Final Boss. To be blunt, you can defeat him simply by spamming one attack, and he's beaten in a way more appropriate for a Looney Tunes short, smashed by a huge piece of machinery dropped from above. The anti-hero protagonist even expresses doubts after doing so that this was the real Mr. Sinister at all.
 * Lester Buchinsky, aka the Electrocutioner, from Batman: Arkham Origins. Yeah, he looks big, tough, and mean, with his Powered Armor and electrified gauntlets, and the game seems to be setting you up for a brutal slugfest with this guy, but then the fight starts and Batman floors him with one punch. He even later tells Alfred how easy that was.

Fighting Game

 * The Shainto clan in Bushido Blade 2 face an insanely difficult boss battle, but after this enemy is finally killed, the player learns that he was merely The Dragon and the true leader of the Narukagami is... an unarmed young woman kneeling in the next room. She patiently awaits her death, but the player can choose to spare her if so inclined.

First-Person Shooter

 * In FEAR, you spend the entire game trying to find Paxton Fettel. You eventually come across him kneeling in a small cell. He starts babbling madly, but one pistol shot to the head takes care of him and his psychically-controlled clone soldiers.
 * Bungie's sci-fi FPS Marathon has you fighting through an entire alien army to find and kill the alien general. But when you find him he turns out to be a deskbound pushover, with no weapons and no attacks.
 * Near the end of No One Lives Forever, the player finally comes face to face with Baroness Dumas (basically the Big Bad, though there is another Boss Battle after her). She has no weapon, doesn't move, and is defeated with a couple of shots from the pistol. Of course at the this point she begins to explode (um... don't ask), leading onto the real point of the level which begins with you encountering her, which is to get everyone away from the area before she blows up.
 * Borderlands 2
 * Face McShooty is a lunatic that you encounter in Thousand Cuts who is screaming hysterically for someone to shoot him in the face, and completing the quest "Shoot This Guy in the Face" requires you to do just that. In fact, doing so gives you the Achievement called "Well That Was Easy".
 * One with more importance to the plot is Professor Nakayama from the DLC "Sir Hammerlock's Big Game Hunt". A Dirty Coward and Nervous Wreck with serious self-esteem issues, he's had nothing but bad luck since his boss Handsome Jack's death. After you fight your way past his biological creations (including the giant, muscular brute Jackenstein, pretty much the actual boss of this mission) he comes out to face you, and you don't even have to fire one shot. In the middle of his villainous rant, he slips on some stairs and falls down them, breaking his neck.

MMORPG

 * In the "While Guthix Sleeps" quest in RuneScape, Lucian summons two Tormented Demons to try to kill you. You touched the Stone of Jas before that, which bumped up all your stats to level 255 temporarily (The maximum is 99, and you can only get about 30 additional levels with potions in comparison). Oh, you also regenerate any lost health during the battle, so if you wanted to you could remove all your armor and punch the tormented demons to death when it is not using Protect from Melee
 * City of Heroes has Sally, the Giant Monster swimming in Lake Salamanca. Tag her with one attack -- any attack -- and she submerges. (And you get a badge.)

Platform Game

 * After you fight the Vizier's magical duplicates in Prince of Persia: The Sands of Time, the actual Vizier takes only one two hits to defeat. One to knock him out a window, then one to finish him after he somehow gets back up and ineffectually threatens you and Farah.
 * Dracula's final form in I Wanna Be the Guy.
 * In You Have to Burn The Rope, the protagonist has unlimited health, and the only boss takes just one hit (from a chandelier) before dying.
 * Adahan, the boss of Planet Scorch in Ristar spends most of the fight at roughly the ideal difficulty. After you've landed the penultimate blow however, the robot mole explodes, and you see it's damaged remains fall from up high. Followed by the pilot, who now tries to continue the fight despite being completely harmless without his armoured suit. He starts crying the next time you hit him.
 * A rare non-Anticlimax Boss example is Bob the Goldfish from the first Earthworm Jim. You reach him at the end of a gruelling tube maze and an insane bathysphere race against time. He floats in his bowl, sneering at you. Any attack, or just touching him, will knock his bowl off the pedestal, leaving him to flop around.
 * In the sequel, Jim will simply eat Bob when you finish the stage.
 * Mega Man Zero 3. After defeating the final boss in his three forms a cutscene follows, paralyzes him, and you get to land the final blow with the saber.
 * Adeline in Kirby 64 The Crystal Shards is a sort-of example. As a miniboss, the monsters she summons through her paintings are actually pretty challenging. However, when Adeline finally attacks you herself, any single kind of attack will defeat her. Even just running into her.
 * Before her, Ado from Kirby's Dreamland 3 ends the fight in the same way.
 * The Brain In a Jar from Space Station Silicon Valley. It's a brain in a jar. It just sits there. You're a killer robot with Eye Beams. The only way you can lose the match is if your console were to short-circuit at some point during the three seconds it takes to fry it.
 * More than one Puzzle Boss has had the trick that they're a Zero Effort Boss—actually trying to fight will at best do nothing, and at worst is the only way to actually lose. The Mirror Prince from the original Prince of Persia is a famous example, as are the dancing skeletons from Monster Party, the Dark Knight from Final Fantasy IV and Gogo from Final Fantasy V.
 * One of the bosses in Kirby Super Star's Arena is a Waddle Dee. Enough said.
 * Not to mention that it just stands there and doesn't even try to attack you with Collision Damage. Though it does notably have more HP than the average Dee.
 * In Kirby Super Star Ultra it now wears a blue bandana like the Waddle Dee in the Megaton Punch minigame, and it can actually walk (slowly) and jump. It's still very easy, however. It also shows up late in the new sub-game "Revenge of the King" as well.
 * The final boss of Bunny Must Die in Chelsea's storyline.
 * Dynamite Headdy has a fairly difficult boss midway through the game called Baby Face, which is a giant head on a pole that shifts through the various stages of life as you progress through the battle. Most of the stages also have a hand on a pole doing various things to try to kill you or screw you up. When you finally reach the Old Man, the final stage, the only attack is a withered hand that constantly shoots up and tries to grab you. If you successfully avoid it and blast away the last mask, you get a bonus point. However, if the hand grabs you, the boss laughs evilly...then promptly dies of old age.
 * In Rayman 2, one would expect Umber, one of the four Guardians (in this case, of the Sanctuary of Stone and Fire), to put up a fight.  Umber explains this in Revolution:
 * The very first boss in Monster Party is simply a crab corpse that apologizes for being dead. There is also a later boss fight against a pair of zombies that can be defeated by just watching them dance as they tell you to.

Racing Game

 * A rare racing example is Big Rigs Over the Road Racing. Due to the game being programmed by monkeys and unfinished, it's impossible for you to lose a race. The AI never moves. EVER.
 * There is a patch to make your opponent move, but it still won't cross the finish line.

Role-Playing Game
"APPRENTICE: Shriek! The boss only wants 7 Snifits! All my training was in vain! What a rip!"
 * Final Fantasy X has, the Post Final Boss of the game and the biggest single threat in the world... except all he does is heal himself and use percentage-based attacks (he only uses Ultima when low on health), so it's very unlikely he'll cause enough damage to kill you, and even if he did, everyone in the battle has permanent Auto-Life so they spring right back to life as soon as they get knocked out. The only way you could possibly lose is by deliberately casting petrification spells on all your characters. Hell, you can even Zombify the boss, and watch as he slowly whittles his own health away with healing magic.
 * In Final Fantasy VII, After the epic One-Winged Angel battle against Safer Sephiroth, (with kickass music) there's one more fight against him in the Lifestream. He is impossible to lose against—the only attack you can do is the Limit Break Omnislash, which kills him in one hit, he can't do enough damage to kill you because his attack is percentage-based, and if you do wait for him to attack, you automatically (whether or not you had the materia equipped) counter with a normal attack which also kills him in one hit.
 * Dramatic example in Final Fantasy V, where all but one of your party members is incapacitated, requiring the one to take on Exdeath solo. Despite laying into him with everything he's got, doing enough damage to kill him several times over, remains standing through sheer force of will.
 * Another example: Famed Mimic Gogo. In the sunken tower of Walse, you can find him at the bottom of the tower. How do you defeat him? Stare at him. Do absolutely nothing, and you'll win. Now, say, what happens if you attack him? He'll counter with attacks that deal 9,999 points of damage, then, if you get him down to a certain point, he'll cast Meteor three times, killing everyone, unless one is using cheats. It is possible to win by killing him before he gets off the three Meteors, though.
 * The Post Final Boss of Baten Kaitos: Eternal Wings and the Lost Ocean offers no resistance whatsoever. Despite having a mountain of HP, his attacks are weaker than most of the mooks you've been facing for the past hour. was the last thing any sane player expected at that point, and it does provide for an interesting bit of story near the end.
 * In Xenosaga II, the very last boss fight of the game is against Albedo, who sets himself up as being godlike and goes on and on about how powerful he is, but
 * The Golem Boss from Chrono Trigger isn't the final boss, but it has plenty of buildup: after you fight the Hopeless Boss Fight against the Golem and defeat That One Boss, the Golem Twins, the game pits you against the Golem Boss in a battle atop an airship. Unfortunately for the Golem Boss, it's too afraid of heights to attack.
 * Some effort is involved in killing the boss before it automatically flees after a set amount of time, however. You can't lose, but you can be denied some juicy XP.
 * Ozzie is also a pitiful excuse for a boss the two times you battle him. His entire strategy is to hide behind a barrier and surround himself with switches that open trap doors (including, bizarrely enough, one that opens under him). If you choose to attack Ozzie directly, he'll counter with an attack that does very little damage; even less in New Game+. The only possible way to lose against him is to continue attacking him directly without ever bothering to heal yourself; do enough damage to him, and you're essentially forced to attack one of the switches.
 * from Wild ARMs 4 injects himself with cells that make him super powerful. Unfortunately all he does is become a giant super powerful traffic barrier with a speed stat of 0. He will never get to act, unless you somehow give him a speed boost, in which case, he just skips his turns.
 * The second battle isn't much better, but at least he counters.
 * In the first two games of the Mario & Luigi series, it is impossible to lose to the introductory tutorial boss.
 * While not technically a boss, the Apprentice from Super Mario RPG should count, since you can't run away from him once he challenges you and will probably go down in one or two hits, and the only way you can possibly lose is if you do nothing but defend and try to run away while he whittles away your HP with Scratch Damage. If you do lose, he will actually be hired as Snifit 4 and appear in Booster Tower, though you don't get anything for it.
 * If you do lose to this Snifit, another will appear in his place. You can actually do this up to five times, and upon losing the fifth time, if you return to Booster Tower, instead of meeting Snifit 8, you'll just find the normal Apprentice sulking in the corner.


 * In Paper Mario, there is Tubba Blubba, an invincible boss with high attack power and immunity to everything. You have to discover his secret and defeat his dragon to make him lose his immunity. Then, turns out he has very low HP, and can be defeated in one single turn.
 * Monstar is the epitome of this. This ghostly creature looks dangerous, but it only has 20 HP and a single attack that does 1 damage. This would be a difficult fight if you didn't encounter it near the end of the game. Even moreso if you have the Damage Dodge badge equipped (which you should), which reduces all damage by 1 (making you completely immune to Monstar's attack).
 * Fable II has this. You've spent the entire game foiling Lucien's plans, he's  Granted, you're given a MacGuffin that renders him powerless beforehand, but still. Come on, Lionhead.
 * Negative Man from Mother 3. He doesn't attack... he just cries and mopes while you assault him.
 * He actually can attack, but it's extremely weak and he attacks so rarely that players may never see him attack at all.
 * Also the story telling robots in Saturn Valley. They actually cannot attack.
 * In Albion, the final boss has the maximum number of hit points allowed by the game engine (which is WAY more than what any other character or enemy in the game has), and is also impervious to physical attacks and 90% resistant to magical ones. His attack also kills pretty much any character in 1 hit. Why is he is a Zero Effort Boss? Because you automatically win the fight after he kills 2 of your party members.
 * The first boss of Secret of Mana is this, as Jema will revive you each time you die until you win. Which is a good thing, because you're probably going to die at least three times over before you can finally kill the bastard.
 * Mega Man Star Force 3. After defeating the final boss, a cutscene follows, showing Mega Man's final form (The one shown on the game box), unlocked. After that, you refight the final boss, who now has an astonishing 8000 HP. This may be daunting, but his attacks can not kill you, even at 1 HP, and the battle doesn't end until you land the final move. (Also dependent on the game's version)
 * The Starman Junior in EarthBound might have been a pretty tough opponent on his own, given he has enough hit points to last him a while and attacks. However, you have a computer-controlled Buzz Buzz with you for the battle, and the bot will always have him put up a shield that absorbs all damage, and to replace it when it runs out.
 * Sol in SaGa 3 just stands there and says "Kill me" so he'll take Xagor down with him. (Suicide by Cop) However, the True Final Boss comes right after that fight; so it's perfect to put on some buffs.
 * The Floor 99 Boss of the Ancient Cave in Lufia 2 is impossible to lose to. He spends 2 rounds healing you, idles for one round, and then kills himself. The trick is to deal 10k HP damage before he kills himself or kill off your own party, if you want his key. Of course, few would know either of those, due to the Nintendo Hard nature of the Ancient Cave....
 * The Gray Prince in The Elder Scrolls: Oblivion, who is your last adversary in the Arena, can easily become this... but only after you do a Sidequest that reveals his true origins . Upon learning of it, he decides that he doesn't want to live anymore and asks you to kill him.
 * The last boss in Persona 3 has a form that does nothing but smile arrogantly, which has no effect. It gets harder afterwards.
 * She does have an attack that hits the entire party for a small amount of Almighty damage, after the first few turns; she's just easy enough to kill that you're unlikely to see it. (All forms except her last one have 1500 HP, and while later forms generally have multiple invulnerabilities and a ton of defense the first one does not and goes down in a few hits).
 * The True Final Boss after that cannot be lost to, even though it deals 9999 damage attacks every round (your health caps at 999) eventually, you just start blocking the attacks, and then on the last round every command is greyed out except the one skill that will finish the fight.
 * The same applies for Persona 4.
 * A lot of the bosses in Valkyrie Profile turn into this thanks to the "--Slayer" type equipment that kills anything in its category in one shot, and which you can just find in a normal playthrough, without going very much out of your way, if at all. The first of these you get is Dragon Slayer, then Beast Slayer, and half the game's dungeons culminate in a boss that fits into one of those two categories. Same goes for weapons with "[Elemental Rock-Paper-Scissors]+DEATH" in its description. In the A ending, one of the final three bosses is susceptible to this because of a weakness to fire.
 * The Boss of the Battle of Karthal stage in Might and Magic X: Legacy is the cowardly rebellion leader Markus Wolf, who combines this with Get Back Here Boss. He flees when he sees you, and you have to fight your way past an army of Mooks and two other Bosses (it's possible to avoid one of them) before you finally corner him. While the chase is not easy, Markus himself collapses if he takes even one point of damage, and your mission is completed.
 * Captain Pete in Kingdom Hearts II, the past-version of Pete that Sora encounters in Timeless River. Unlike the present version of Pete ("Bad Pete", as he's called) Captain Pete is a weakling and coward, and not exactly a bad guy either, and Sora effortlessly takes him down before realizing this. Unfortunately, Captain Pete gets  an even worse shellacking from Bad Pete when the villain finally shows up.

Shoot'Em Up

 * Almost every final boss in the Gradius series is the Bacterian emperor, who usually takes the form of a large brain and either fires easily-avoidable attacks or just sits there and does nothing, giving the player a chance to take him down. On the other hand, given that it's in control of the space station you just cruised through, maybe the whole level counts as the final boss.
 * Special mention goes to Gradius III, in which the Bacterian emperor mutters some incomprehensible curse, starts vomiting really slow purple energy balls in a gentle curve, and spontaneously explodes fifteen seconds later (or sooner, if you fire at him). At least he actually fights back, which is something of an accomplishment considering the last two final bosses of Gradius didn't even do that. In the arcade version, getting hit by its attacks doesn't kill you, but instead teleports you to a Nostalgia Level based on either Gradius 1 or Salamander. Finishing it or dying in it takes you to the last checkpoint before the final boss.
 * Another special mentions goes to Gradius Rebirth, in which the final boss sics a large group of on you to defend itself while taunting you. While annoying in that they , they can't actually destroy you.
 * The final boss of Salamander 2, Doom, is an exception. A major one. Venom in Nemesis II is an exception too.
 * The Final Boss of Space Invaders Infinity Gene is . It's still possible to get killed (but you have infinite lives in that sequence), and it's also possible for the invader to reach the bottom of the screen. Whether you beat it or not, the game is still completed.
 * The Final Boss of R-Type 3 is no pushover, being fought in a Negative Space Wedgie. However, after (seemingly) killing that boss and returning to normal space, it will hold the Negative Space Wedgie open, ostensibly to come after you. However, its attacks are stupidly easy to dodge after the boss fight you just went through, and you can (must) kill it in one hit by smashing its face with your Force Device.

Simulation Game

 * Terminal Velocity, World 3 boss. When you destroy the large building, a large turret is deployed in its place. Because of how it aims at you (by facing rather than tracking), it takes effort to dodge into its attacks

Stealth Based Game

 * Tenchu has a few bosses that follow this. In the original Tenchu: Stealth Assassins, the boss of the first level is an old merchant who goes down in one or two hits. It IS possible to lose to him if you're low on health and let him shoot you with a gun, but you have to be trying to lose. In Tenchu: Fatal Shadows, you have an early encounter with the Big Bad... who leaves while his lover volunteers to fight you. She is a defenseless Geisha girl with a small dagger who goes down in one hit. It may be impossible to actually lose unless your health is at the bare minimum and you let her attack.

Survival Horror

 * In the remake of Resident Evil, you have to deal with Neptune, a Zombie Great White Shark. Sound tough? It would be, except since you drained the shark tank, all it can do is feebly flop around.
 * Note that however if you screw around when he's splashing, chances are, you may climb down and get eaten.

Turn-Based Strategy

 * In Fantasy General (an old Panzer General spinoff) you fight dozens of battles across six continents to stop the Shadowlord and his vassals. Once you reach the fifth continent, the Shadowlord will cast spells at your troops each turn. However, when you finally reach the end of the campaign and storm his castle, he will get destroyed without a fight, being unable to stand against the the pure goodness emanating from you.

Wide Open Sandbox

 * The final confrontation in The Saboteur with Nazi Officer Kurt Dierker on the top of the Eiffel Tower. It is actually not as epic as it sounds..
 * The last enemy of Killer7,, does nothing but run away from you in a shadowed corridor until you corner it, then stand still cackling while you shoot it to death.
 * from Grand Theft Auto IV: The Lost and Damned. Though the preceding level involves blasting your way into the prison to reach him, once you do, he is unarmed (as he's a prisoner) and you just shoot him down.

Anime and Manga

 * Deliora from Fairy Tail. After all that effort to stop its awakening, Natsu and Gray fail. It awakens, roars, and...
 * Dolph in Nichijou has pretty much all the troops in the airship under his command, the princess helpless...
 * in the Marineford arc of One Piece. It's implied that he let Luffy win.

Web Original

 * Sonic the Hedgehog 2 Special Edition nerfs the original game's end bosses - Wing Fortress's is fought as Super Sonic, Silver Sonic merely leads you to the final boss, who dies with one jump.

Western Animation

 * In The Owl House episode "Young Blood, Old Souls" has two. Warden Wrath tries to put up a fight against Luz, but is curb-stomped quickly and reduced to pleading for his life (an obvious case of Villain Forgot to Level Grind); a couple of scenes later, Kikimora - Emperor Belos' assistant - doesn't even try, cowering from Luz and quickly giving her the information she wants. Of course, this could have just been Pragmatic Villainy on her part, seeing as Wrath is about twice her size and Luz had also beaten up most of Belos' goons by then.

Real Life

 * Roman Emperor Claudius once fought a whale as a gladiator, with both combatants stuck on land (descriptions of the event indicate the whale was not intentionally put there). Critics were not impressed. Other Emperors are said to have fought in similarly impossible to lose matches. This trope is thus Older Than Feudalism.
 * Dio Cassius, a Roman writer, once claimed that the Roman Emperor Commodus gathered up all the sick and injured people in town, gave them SPONGES TO THROW as weapons, and killed them by hitting them with a club, pretending they were giants.