There Can Be Only One

"In the end, there can be only one."

—The Arc Words of Highlander

The long-term plot of the program revolves around a group of characters whose numbers are being slowly whittled away by one means or another, usually by killing each other. In the case of some reality shows, this is a process of elimination intended to result in a single winner. In other shows, this is a dramatic device, designed to generate tension and conflict with which to drive the overall plot of an episode or Story Arc (if any); in these cases it is sometimes combined with Anyone Can Die to especially heighten the resulting excitement, even when the apparent main character may be protected by Contractual Immortality. Compare Gotta Kill Them All.

Does not apply to pure game shows, as they have no overall storylines for the elimination to serve. Compare Dwindling Party, where it's less a competitive elimination and more a bloody murder spree.

Named for one of the catchphrases that came out of the Highlander franchise.

Examples of There Can Be Only One include:

Anime and Manga

The anime My-HiME starting around its sixteenth episode (this arc was nicknamed "HiMElander" by fans, as a reference to Highlander).
Another anime, Fate/stay night involves seven mages who summon spirits of heroes to fight each other. The last spirit standing gets the Holy Grail, which grants a wish. (Killing a mage is a good way to get at the spirit they summoned.)
- And it's really 'only one' because humans can't touch the Grail, so the Servant does it. And then they get sucked in and turned into fuel like the others for the wish of the Master. By this point, nobody really remembers the mechanics of how it works anymore because no one's ever won. Well, technically Kiritsugu won the last one, but that didn't count.
Yet another anime, Rozen Maiden, has as a central plot element an informal tournament-of-sorts cheerfully called 'the Alice Game' wherein the magical doll characters have to compete for the Pinocchean prize of becoming the perfect girl—by slaying all their sisters. Better Than It Sounds, though.
- It's implied that there's another way to win, though.
The central plot of Gash Bell is that there are 100 demon children sent to the earth, with the remaining one being able to reign as king for 1000 years.
Sekirei. There are 108 of them, fighting to be the last one standing. Each one of them is bound to an Ashikabi, or master. As proven with Minato's Harem of Sekirei, the "last one standing" rule applies to the Ashikabi than the Sekirei themselves.
- Furthermore, having an Ashikabi killed will immediately disqualify all his or her Sekirei. Fortunately, Ashikabi are normal humans and protected by the legal code—Sekirei are forbidden from attacking them directly.
  - Then again that game is full of cheating bastards.
Bokurano. And it's twisted as hell too. Basically, we need to thin the alternate universes down to just one. So, let's have kids fight in gruesome giant mechs! Win, YOU DIE. Lose? EVERYONE IN YOUR UNIVERSE DIES. Look up "no win situation" in the book, you'll see this. Needless to say, this utterly screws with the child pilots' minds.
X 1999 does this with two groups of seven fighters, the Dragons of Heaven and the Dragons of Earth. The Dragons of Heaven fight to preserve the world, but if the Dragons of Heaven are all defeated by the Dragons of Earth, then the world will end.
- That is "end" in terms of "as we know it." The world will continue, but mankind will be wiped out. Or that is what some of the Dragons of Earth seem to think will happen. This is a rare series in that none of the villains are out For the Evulz or, mostly, For the Lulz. Some are closer to that the former, though. At the end of the day, there's no character incapable of being seen as an Ensemble Darkhorse.
Basic premise of Mirai Nikki: God rounds up twelve not entirely well-adjusted individuals, gives them all limited precognition, and commands them all to fight to the death so that the last one standing can become the new God.
The Law of Ueki is based on this trope. Middle School Students are picked by God Canidates to fight against each other, and the last one standing gets a special talent of their choice.
Pluto revolves around the title villain systematically hunting down and murdering the seven most advanced robots of the time. Gesicht's challenge is to apprehend Pluto before the same thing happens to him.
- This was also the plot of the original Astro Boy story that Pluto was based on, called "The Greatest Robot on Earth".
Invoked by Metal Sonic in the Sonic the Hedgehog OVA's--"There is only one Sonic the Hedgehog." Metal follows this to the bitter end: After Sonic defeats him, he falls into a pit of lava. Sonic tries to pull him out, but Metal brushes his hand aside.
Princess Resurrection: Every new generation of Royals must kill each other off until only one is left to Ascend to a Higher Plane of Existence.
Death Note Somewhat exercises that trope, with the ongoing battle between Light and L. Both of them are won't stop pursuing each other until one of them is dead. This is extended to the fact that Light is willing to kill Misa and his other followers to achieve his goal as god of the new world.
G Gundam takes this trope to a very strange place: every four years, the nations of the world participate in Combat by Champion, sending their strongest fighter in a Gundam to Earth to participate in a giant tournament. The last Gundam standing wins leadership of the council of nations for the next four years.
Cowboy Bebop is a great example of this. From Spike's Mafia days, Shin dies a while back, his brother Lin is killed, Mao is killed, Annie is killed, Julia is killed, and Vicious repeatedly remarks to Spike that only they can kill each other.

Comic Books

In Rising Stars, there are 113 specials, and in the first issue it is revealed that there will only be one left 60 years after they are born. This becomes especially important when we learn that whenever a special dies, his energy is transferred to all of the surviving specials, making them stronger.
- Even more important as in this universe all superheroes are slowly using up the energy that gives them their powers. So if a character wants to remain super on the long run, his only choice is to...Well, you can guess the rest.
Larfleeze is the only true Orange Lantern Corps member. Overcome by greed, they all fought until he was the last one standing. Then Lex Luthor gained a second orange ring, and the fight has begun again.
At one point the main man Lobo died. Luckily, he can regenerate from a single drop of blood. Unluckily, there were several thousand drops of blood splattered across a battlefield. So, several thousand Lobos found themselves in one place—and what followed was a awesome and horrifying deathmatch, until only one Lobo remained.

Film

Highlander, the trope namer itself, has immortal beings which can die only by decapitation, killing each other until the last one standing obtains all knowledge of the world and the right to spend the rest of his/her life as a mortal.
The One had a man jumping from dimension to dimension to kill off Alternate Universe versions of himself, in order to gain power.
How I Won The War has a variation on this. When people are killed, they became a coloured (meaning they turn into red, blue, green etc. version of themselves, not that they turn black) version of themselves, but still can help. Only the main character survives at the end.

Literature

Battle Royale is a particularly brutal example due to the adolescence of the characters.
...as is The Hunger Games, where this is a Zig-Zagging Trope: With only a few competitors left, the Capitol makes an announcement that if the last two survivors are from the same district, they will be co-winners. Katniss and Peeta become the last two survivors, but the Capitol lied, and there will only be one winner after all. They decide to commit double suicide rather than attempt to kill each other, and the Capitol backs down, deciding that having two winners is better than not having any.
This is Gilbert Norrell's attitude toward magic. In fact his chief concern as officially sanctioned magician is to make sure there are no other magicians in Britain.
Stephen King's The Long Walk (written as Richard Bachman). The last one to be alive is declared the winner.

Live-Action TV

The various installments in the Survivor franchise, as well as most other competitive reality shows.
The plot-central Scions of Revelations both play this straight and (slightly) subvert it: the Final Battle will occur when there are exactly two of them, leading some people to try killing them off to speed things up, while others seek to save them in a Race Against the Clock... but not all the Scions are known, and some of the claimants are bluffing, deluded, or already dead (no, really!). There is always a feeling that their numbers are running out, but it isn't clear until very late exactly how close things are.
The duel of the 13 Riders in Kamen Rider Ryuki.
- This occurs in the Kamen Rider Decade movie where Decade, having embraced his role as the Destroyer of Worlds, sets out to defeat every Kamen Rider.
- This also occurs in Kamen Rider Black on a smaller scale. A duel between two riders in a contest of who is to be God.
In the universe of Wizards of Waverly Place, only one child per wizard family (the winner of the wizard contest) is allowed to keep his/her powers and become a full wizard.
Implied in season 6 of Lost, with the revelation that several main characters are candidates to replace Jacob as protector of the island, but only one will be able to actually fill this role.
This trope is most of Sylar's plotline in Heroes, in Season 1 especially, and in Season 3:Volume 4 when he teams up with Danko to eliminate them all, there are also the following lines:

Danko: If we do this - if we succeed - you'd be the only one left.
Sylar: Funny how that works.

In the Season 10 premiere of Smallville, the old Lex clone states that "there can only be one Lex Luthor" before using an improvised flamethrower on the other clones.
On the Angel Season 5 episode "Destiny" Lindsey and Eve deceive Angel and Spike into believing that the existance of two champion vampires with a soul is causing universal chaos.
In Community episode Modern Warfare only the last man standing will receive the prize.

Radio

As much as the defenders on Canada Reads might like some or all of the books up for discussion each year, only one book can be named the book that Canada reads.

Tabletop Games

When the Druid and Monk classes were first introduced to Dungeons & Dragons (in the Greyhawk and Blackmoor supplements, respectively), the rules restricted the numbers of higher-level characters in the classes. If you wanted to advance to the upper echelons, you had to defeat one of the characters who already held that rank. At the highest levels, each class allowed only a single individual. This carried into the first edition of Advanced Dungeons and Dragons.
- The first edition of AD&D had much the same thing going on with Assassins. The highest two levels, 14 and 15 are reached by taking over an assassin's guild by killing the Guildmaster (a 14th-level assassin) and by finding and killing one of the existing Grandmasters in order to reach Grandmaster level (15th) yourself.
The Wizards of High Sorcery in Dragonlance function the same way, although at least in the case of the White and Red robes murder isn't the best way to get to the top rank.
Regardless of game, if a Collectible Card Game has a variant rule where only one copy of each card is allowed in a deck, it is known as "highlander" format. The most famous and widely played example is Magic: The Gathering's Elder Dragon Highlander which features this among several other rule changes.

Videogames

The Baldur's Gate series basically revolves around the mortal children of the God of Murder, who he created before his death to inherit his power and become his successor. In the first game, one of his sons plans to start a brutal and bloody war to use all the fallen as a sacrifice in a ritual that will turn him to the new God of Murder. In the Grand Finale in the addon to the second game, all the remaining children start to hunt down and kill each other to absorb all the fragments of their fathers divine power and become a god. The god in question actually planned for them to all die so their energy could be used to bring him back to life. Of course, this doesn't go quite as planned either... and the player character can take his powers at the end of it all. Without killing absolutely all the others, since Imoen can give up her share of the power voluntarily.
Digital Devil Saga had a concept similar to this, with individuals replaced by entire tribes fighting each other for dominance. When a tribe's leader is defeated, the remainder of the tribe must swear loyalty to the victor, and this continues until only one tribe remains. The winning tribe then gets to ascend to Nirvana.
Blanca's Wolf Bout Sidequest in Shadow Hearts: Covenant is based around fighting the other wolves in the world to prove his strength. The last battle is against Ernest, the man who told you about the tournament to begin with. He reveals that he was a hunter who wanted to isolate the strongest wolf in the world to test himself again. And he fights you in a fursuit. Victory earns you Blanca's special moves and ultimately his Infinity+1 Sword.
The modus operandi of Big Bad Nemesis in Black and White: he spends the game killing off all the other deities so he can Take Over the World.
In Persona 3: FES, the ex-SEES members discover that they can break out of the Time Skip by assembling the eight fragments of the Key of Time, of which each of them possesses one. Naturally, a disagreement breaks out over how to use this power (more specifically, whether to go back to the past or continue in the present); they solve it by arranging a four-way fight, with the members all pairing off against one another.
No More Heroes revolves around Travis Touchdown, 11th best assassin in the United Assassins Association, working his way up the rankings by killing off the top ten one by one.
- Though one of the series's themes, which started near the end of the first game and is rampant through the second one, is that there will always be more assassins coming up from behind, so there will never really be "just one".
This is the driving point behind Unreal Tournament's Last Man Standing mode.
Two of Big Boss's three clones claim "The world needs only one Big Boss!" The third clone, Solid Snake doesn't buy it.
- When Big Boss reappears in Metal Gear Solid 4, he says "The world needs only one... No, the world would be best without Snakes."
In Shin Megami Tensei: Devil Survivor, the King of Bel has the power to command all of demon-kind. To become King of Bel, a being with a fragment of Bel's original power must defeat all of his fellows and absorb their fragments as well. The player character is one of them, the only human Bel. This gets him hunted by several powerful Bel demons... until he starts hunting them down instead.
There can be only one Prince of Darkness!
Team Fortress 2: If one melee-equipped Demoman defeats another such "Demoknight," he will sometimes scream "THERE CAN BE OOOOOONLYYYY OOOONEE!... Eye."
- This is essentially the typical outcome of any match played in Arena mode. There is no respawn and to win each team has to kill everyone opposing them. More often than not, the winning team has only one or two people still standing.
The whole point of Twisted Metal is Calypso staging an annual Vehicular Combat tournament where drivers ranging from ordinary dudes to complete psychopaths kill each other until only one emerges victorious and claims the grand price of one wish of whatever the heart desires. However, as tempting as wishing for anything is, there are always consequences...

Webcomics

Parodied on Ansem Retort. Season Six started with the casts of various reality shows being brutally murdered. Upon finding out they're the only cast left, Axel declares, "WE'RE THE FUCKING HIGHLANDER OF REALITY TV!"
Also spoofed in the Harry Potter parody comic House Sparklypoo. The members of the titular house discover to their horror that they're losing their specialness. Their teacher suggests that it's because each of them is supposed to be the best, but obviously only one person can be the best at anything. Cue massive throwdown as the Sparklypoos try to kill one another in order to regain their special powers, culminating in the destruction of Sparklypoo Tower by an errant Dragon Slave.
R2-D2's player from Darths and Droids claims that if he were to clone himself, "We'd fight to the death, and the winner would be the new me."
In El Goonish Shive, this is possibly subverted; while Lord Tedd is supposedly out to kill the "weak Tedds," Nioi insisted that he was misunderstood, and it is clear from various hints that he has a Freudian Excuse lurking in the shadows. Unfortunately, due to the Kudzu Plot, he's been Put on a Bus, so it'll be some time before we find out why.
In Impure Blood, this was the rule of the Gladiator Games. Roan lasted for years—and finally escaped.

Web Originals

Survival of the Fittest. It's based off Battle Royale, therefore this should also be fairly self-explanatory. For those of you not in the know, the idea is that an island full of students are to kill each other until there is only one survivor.
The Kazahana Family Mass Battle web collaboration by Lifepoint One Entertainment focuses on a family whose first head has decreed that the legacy of his fortune be sealed, and passed onto a direct descendant of his own blood, 600 years after his death. One of the Kazahanas, unsupervised by the others, sowed his seeds far and wide, and 600 years later, there are now hundreds of Kazahana descendants, and with only one of them destined to claim the fortune, the stage is set for a bloody and violent battle.
Being based on Fate/stay night, Fate Nuovo Guerra follows this convention, though exactly how long until one is left is vaguer, as the 'seven mages' limit has been removed.

Western Animation

How Leonard of Ugly Americans regenerated after Mark accidentally killed him. Though it wasn't supposed to be that way, the regeneration urn holding his pieces together broke.
THERE CAN BE ONLY ONE!!!...nice.
Kim Possible's Mission Control Wade says this to Rufus after it becomes apparent that, thanks to some brain-enhancing machinery, the naked mole rat might be smarter than him. Wade must take his role as the Smart Guy very seriously.

Real Life

United States Presidential Campaigns. This show lasts for over a year, with plenty of suspense and commentary. The losers get to make tearful speeches, either endorsing the winner at the convention, or conceding defeat in the general election. A nonlethal example, the Consolation Prize usually being either a Cabinet postion or the lecture circuit depending on whether or not one's party wins.
The Roman Emperor Diocletian chose to divide it into two parts (east and west), each ruled by an Augustus (Diocletian in the east, Maximian in the west) assisted by a Caesar, who would, on the death of the Augustus, take his place and appoint a new lieutenant-emperor. This system meant there would always be at least four people with imperial rank. It worked well initially under Diocletian, but, within a generation of his death, the whole thing was back under the control of a single emperor (Constantine the Great) via forcible removal of the others.
For unexplainable reasons, the human race is constantly trying to find "the best X of all time", all the time.
Tournaments. Any kind. Sports, Chess, Video Games... The whole point is to keep pairing people/teams up until only one remains and is declared the winner.