Forced Prize Fight

Combatants are forced by the "powers that be" to brawl, box or otherwise fight. Sometimes to the death. The Hero is sometimes caught up in it all or may deliberately go in undercover to expose the racket.

Occurs most often in prison and prisoner-of-war settings.

A common variation has our hero assigned to a trainer, in order to prepare him for his most deadly fight -- when the fight commences, he discovers that his trainer is to be his opponent.

See also: Deadly Game, Gladiator Games, The Boxing Episode, Hunting the Most Dangerous Game, David Versus Goliath, Achilles' Heel, Tournament Arc, Involuntary Battle to the Death and possibly Combat by Champion. If prisoners are involved it's a Condemned Contestant fighting to Win Your Freedom.

Anime and Manga

 * The second episode of Weiss Kreuz is based on this trope: Fujimiya Aya goes undercover as a participant in so-called Human Chess prizefights.
 * This happens in the Coliseum episodes of Kino's Journey, when Kino is forced to fight to amuse a country's insane despot.
 * There's the trainer variation in Mahou Sensei Negima, . It was almost going to be used in the Mahora Fest, but then   But she MEANT for that to happen.
 * Golgo 13: In "The Brutes' Banquet" 2 bloodsports followers have Golgo duel another assassin to see who wins.
 * During the Chuunin exams in Naruto, all the genin have to fight each other to advance, though naturally, the only kids from the same village who get matched up are those with scores to settle, and everyone else gets paired with a foreigner.
 * Except Naruto and Kiba. And Sasuke and Yoroi. So really only half of the Leaf v. Leaf fights.

Comic Books

 * Similar to the Justice League Unlimited examples below, the Roulette storylines in JSA and JLA Classified.
 * And War World was also based on a storyline in Superman comics.
 * One Bronze Age comic set this up between Superman and Muhammad Ali.
 * Some of the Superman/TheFlash races were like this.
 * Only the ones "for charity", anytime the Flash really bothers to actually TRY it's way too much of a Curb Stomp Battle to count
 * The Punisher went through this once. While chasing a mob goon across roof tops, both of them end up crashing into a ring where they're forced to team up to survive. At the end of the story, the thug thinks he has won Frank's respect, but the next day Frank tracks him down and kills him.
 * In the Batman/Wildcat mini-series, members of Batman's Rogues Gallery are kidnapped and forced to fight one another in a series of cage matches.
 * The concept behind the Dark Side Club in The DCU.

Film

 * Tron: The Master Control Program forces other living programs who defy it to participate in video games-which for a program are battles to the death.
 * Mad Max: Beyond Thunderdome
 * Escape From L.A. (In a variation, Snake Plissken, an unbeatable dirty fighter, has to win a steel-cage basketball game in order to escape. The danger coming from the fact that if he doesn't make enough goals, he gets shot to pieces)
 * Notably, the game is impossible: it requires scoring 25 points (standard basketball rules apply), crossing the court each time, in 60 seconds. Which makes the fact that Snake succeeds all the more Badass.
 * The last shot is full-court, and Kurt Russell actually made the shot in real life.
 * In the first Plissken film, Escape from New York, it's a more conventional boxing/wrestling match he's forced to participate in.
 * Virtually any gladiator movie
 * In The Dark Knight, it is implied that the Joker has the thugs of a crime boss he has just killed fight to the death with a broken pool cue, as he "only had one opening" in the gang he was forming. Being the Joker, it was almost certainly for his own amusement.
 * The premise of the movie Bloodlines: a family of inbreds seeking new blood abducts girls and forces them to fight to the death to determine who the strongest is; the "winner" is then forcibly impregnated.
 * Unleashed (aka Danny the Dog)-- Danny (played by Jet Li) is entered into such a tournament by the gangster who essentially owns him.
 * A major subplot of Snatch involves first getting the Irish Traveller fighting machine Mickey into a fixed underground boxing match, and then forcing him to actually go along with the fix.
 * The 2009 Astro Boy film has one of these in the robot games.
 * In Spartacus, the titular character is forced to fight right near the beginning for the amusement of Crassus and his companions, despite Batiatus's attempt to save him from fighting.

Literature

 * The novel Hard Rain (not to be confused with the film, which is not related) has titular character (and hitman) John Rain go undercover in order to find a Fight Club like this. He winds up killing his opponent.
 * In the Sword Dancer series, Tiger is forced into a sword dance to the death he'd really rather avoid when Del is taken hostage. Fortunately, he's able to Take a Third Option.
 * Tiger and Del are professional duelists. They're both forced into duels with people they didn't think they'd have to fight, or don't want to fight, quite frequently.
 * In Dead Witch Walking by Kim Harrison, the protagonist, having transformed into a mink in order to spy on the Big Bad, is caught and entered into a fighting competition with other small mammals. When one of her opponents turns out to be a transformed human himself, they coordinate an escape together.
 * The rat-coursing pit in The Amazing Maurice and His Educated Rodents.

Live Action TV

 * The A-Team episode "Pros and Cons"
 * Angel, "The Ring"
 * Also pops up at least once in the comics and one 'Buffy' tie-in novel. The tie-in writers seem to like making Buffy fight Angel.
 * The Sentinel: a prison warden has prisoners fight each other at night. Anyone who knows is either part of the scheme or knows that they will be killed if they tell others.
 * Racked Squad: in 'The Knock-Out' a con game group stages boxing fights that are said to be rigged. During the fight the victim attends, one of the fighters fakes his death in the ring. Then the victim is convinced that going to the police or Boxing Commission will result in everybody being indicted for manslaughter.
 * Star Trek: The Original Series, "Arena", "The Gamesters of Triskelion" and several others.
 * Homaged in the Futurama episode "Where No Fan Has Gone Before".
 * Star Trek: Voyager, "Tsunkatse". Includes the trainer-becomes-opponent bit. And a guest appearance from The Rock! (fighting Seven Of Nine. No weight classes here!)
 * Stargate SG-1 episode 908 Babylon.
 * Happened in an episode of La Femme Nikita, when Nikita infiltrates a club that compels women to fight with pain collars.
 * In Rome, a bored Mark Antony forces two prostitutes to swordfight for him while dressed like amazons. He watches from his bed, insisting that they "really fight!"
 * Similarly, Pullo is forced into the Gladiator arena as punishment for a murder. Totally disheartened, he refuses to even lift his sword and waits for execution. The other gladiators taunt him until they find his Berserk Button: taunting his old Legion. He promptly kills them, earning his Crowning Moment of Awesome. One final gladiator comes out to finish the job, only Lucius Vorenus jumps into the ring and earns his Crowning Moment of Awesome.
 * Similar to the Justice League example above, an episode of Birds of Prey had Huntress be captured and brainwashed into fighting other super-powered women.
 * Occurs in the first episode of Lost Girl after Bo discovers her Fae background.
 * Merlin "The Coming Of Arthur", after Merlin and Arthur and,seperately, Gwaine are captured by slave traders. There's an attempt to make Merlin fight Gwaine, but Arthur steps in.

Newspaper Comics

 * Happens in the Modesty Blaise "Those About to Die" storyline.

Video Games

 * Video game example (Subversion?): In Breath of Fire 3, the main character is put into this situation, in the "win or die" version. He loses, but as he is the prize demanded by the winner, he is let off the hook.
 * Happens in the Xbox game Fable I. In which, at the end of the Tournament Arc, you have the option of killing your character's childhood friend after besting her in combat in exchange for exorbitant amounts of money.
 * Exorbitant? you get three times that if you make it through the arena without leaving.
 * In Grand Theft Auto IV: The Ballad of Gay Tony, Luis is forced to enter a cage match and take a dive in order to pay off his mother's debts.
 * Fallout 3 has one in The Pitt DLC: after getting captured by slavers and forced to scavenge steel ingots, the second primary quest of the DLC has you using all the equipment you gathered during your scavenge operation in pitfights against other slaves. The fight is to the death and at the beginning, the slavers dump several barrels of highly radioactive sludge into the pit to give you an additional incentive at winning quickly (before you reach 1000 rads and drop dead). There are three fights; winning the third will make the slavers impressed enough that you're freed from slavery and given all your stuff back.

Western Animation

 * Celebrity Deathmatch had a couple episodes where fans voted for a deathmatch between two celebrities that had no reason to dislike each other. The league then invoked this trope with the "Fan of Fandemonium" - a giant bladed ceiling fan that lowered down towards the ring if the two celebrities didn't hurry up and kill each other.
 * Justice League Unlimited, "The Cat and the Canary" and "Grudge Match". Both featured a secret underground super-powered fighting circuit run by the villainess Roulette. The latter episode resorted to mind control to effect girl-on-girl Catfights.
 * Justice League also had "War World".
 * Ben 10 episode "Grudge Match" pits Ben against a more-than-willing-to-beat-the-snot-out-of-him Kevin, as well as other alien gladiators after being teleported from Earth.
 * The Teen Titans episode "Winner Take All" actually dupes Robin, Cyborg, and Beast Boy into fighting each other and other "heroes" for so-called fabulous prizes.
 * Megas XLR features this trope in two episodes, wherein Coop must fight other robots and ultimately the promoter, Magnanimous (expertly voiced by character actor Bruce Campbell).
 * Happened in a Samurai Jack episode when he was very much forced into fighting in "The Dome of Doom."
 * Also occured in another episode with a twist: Jack had been transformed into a chicken.
 * Frisky Dingo: "Penultimate Fighting" has Killface and Barnaby (i.e. Xander Crews) forced to fight to the death to get Simon back.