Sometimes, a GameMaster doesn't have enough players to run a decent game. Or else, he just wants to have his cake and eat it too. Or perhaps the campaign needs a MrExposition and the rest of the party doesn't fit the bill. Either way, he starts out an important {{NPC}} to travel with the party and fill any [[AnAdventurerIsYou missing roles]] no one else wants to play. It's almost like the GM has a PlayerCharacter of his own, thus this concept has come to be known as the GMPC.

Admittedly, this kind of character [[TropesAreNotBad can be done well]] - adding flavor to the campaign and immersing the players in the world the GameMaster has set out to create. This kind of GMPC often serves as a NonActionGuy in order to avoid stealing the spotlight from the players, or at least some form of WhiteMage (passive [=GMPCs=] often end up in the 'healing' role).

However, it's all too easy to screw up the GMPC, especially since the Game Master also controls the game world and plot. Thus, the GMPC turns into a plot device to [[{{Railroading}} keep the players on track]], stopping them from going OffTheRails. Even worse, the GM can take too much of a liking to his PC, and the character slowly but surely turns into a MarySue: defeating all the enemies singlehandedly, doing all the cool stuff, and gradually reducing the players to [[SpotlightStealingSquad supporting roles]]. He might also set up the adventure [[ThisLooksLikeAJobForAquaman to suit his character]], without considering the others.

This kind of GMPC quickly earns the [[CreatorsPet ire of the players]], since what's the point of even playing the game if all the DM's going to do is [[AccidentalInnuendo play with himself?]] They came to the gaming table to [[TheRoleplayer play as fantastic characters]], [[TheRealMan crack some heads]], and [[TheLoonie have fun]]; not sit and watch some MartyStu kick werewolves through buses (and in the case of the {{Munchkin}}, ''he'' wants to be the one kicking the werewolves through buses). This may lead them to try to [[OffTheRails kill the offending character]], which inevitably fails because of countermeasures including [[GameplayAllyImmortality unstealable Rings of Invincibility]] and hostile allies [[RocksFallEveryoneDies getting struck by]] [[BoltOfDivineRetribution 10d100 lightning bolts]]. The GameMaster may quickly find himself without a game if he doesn't get a clue.

An equally problematic variant is the GMPC who is [[JerkAss obnoxious]], [[TheLoad absolutely useless]] or [[TheMillstone worse]]. These characters exist mainly to cause trouble for the players through their [[TooDumbToLive sheer incompetence]], yet they are too pivotal to the plot and/or the fate of the world for the [=PCs=] to leave them to their justly deserved fate. This has all the problems of an EscortMission in a video game, compounded by the fact that the Dungeon Master is doing it intentionally, rather than because of the inferior AI of a game.

It should be noted that any campaign setting that contains significant canon [=NPCs=] (such as the ForgottenRealms) may fall victim to this if the GM insists on having them travel with the party. Just as bad is the habit of using them as a DeusExMachina to bail out the party when they screw up, especially if you set up the [=PCs=] to [[HopelessBossFight fail on purpose]].

Some games, on the other hand, require the GameMaster to have a GMPC, usually a NonActionGuy with some kind of authority over the PlayerCharacters.

There ''is'' a middle ground, a GMPC who behaves pretty much the same as most player characters, but you don't seem to hear much about them. Presumably because they don't make as exciting stories. A GMPC may be employed temporarily to stop new players from killing themselves before they've learned. It can also occur legitimately in a campaign where the role of GM rotates among the players.

(It should be noted though, in general, a GMPC in any game isn't going to solve any issues, come up with ideas, or take charge of any plot important situation the GM has set up for the player to do (unless he's not a very good GM prone to RailRoading). Normally, this is fine when they're just an equal to you mook; this can get comical and bizarre if the GMPC is supposed to be your superior and/or a wizened, experienced character and the GM needs them to be incompetent, silent, or magically not available during crucial moments meant to be handled by the PC.)

Not to be confused with [[UsefulNotes/{{UNIX}} Gnome]] Music Player Client.
----
!!!Examples of games requiring {{GMPC}}s:
* BlissStage's Authority Figure is one of these. Notable as one of the possible results of getting to OneHundredAndEight points of Bliss is for a Pilot to mutiny and take over LaResistance: If this happens, that pilot's player ''must'' become the new GM!
* MyLifeWithMaster in a nutshell: The PC's in this game are the Igors to the Game Master's Dr. Frankenstein GMPC.
* MaidTheRPG is a sendup of the entire {{Meido}} trope in which the [[{{GMPC}} Master]] can have a powerful artifact known as the [[Manga/DeathNote Desu]] [[MemeticMutation Note]]. ...Do I really need to say it?
** ''And'' the players' effectiveness depends on seeking out (or contending for) the Master's approval. On the other hand, the way the rules are set up, Masters tend to be pretty helpless in everyday situations (for the game's definition of "everyday"), and players usually have an explicit power to randomly derail plots they don't like, so it balances out.
*** It's notable that the author's self-insert GMPC gets accidentally killed by his maids. Twice.
* The Wild Card in "MeddlingKids", a table-top game for kids based very loosely on mystery shows of the ScoobyDoo kind.
* NinjaBurger has the dispatcher, a Non Action Guy. His job is to watch the [=PCs=] on closed circuit camera and basically provide them with hints and assistance as needed.
* Not a requirement, but DontRestYourHead has an optional rule where there is no assigned GM, and whoever gets the best roll in a scene gets to control the story, essentially making them the owner of a GMPC for a short time. You would expect this to cause problems, but considering the crowd that game draws in, it actually makes things quite interesting.
* The {{Ringworld}} RPG requires players whose characters mutate into [[CursedWithAwesome protectors]] to give up control of the character to the GM. Protectors have superhuman strength and intelligence, but no free will, as they are ruthlessly devoted to ensuring the survival of their bloodline or species.
* TabletopGame/{{Paranoia}} not only has the Computer, but also specifically encourages the GM to be antagonistic towards the [=PCs=] and cheat when necessary.
* Many PlayByPostGame forums encourage the GM to have at least one character. Of course, these games don't always need a GM.
* Pretty much all games with some sort of "corruption" mechanic will have player characters who go down that road too far eventually lose their status and turn into {{NPC}}s. As a rule, that's ''not'' this trope unless a player who's lost a character to this takes the GM seat and decides to bring their old character back.

!!!RPG Webseries with {{GMPC}}s
* Gandalf is a pretty hilarious example of the kind of things that go on with them in Webcomic/DMOfTheRings.
* ComicStrip/KnightsOfTheDinnerTable BA's are generally assistants (Gilead, Knobby Foot) ands put-upon {{Butt Monkey}}s whose sole purpose are to be kicked around by the [=PCs=]. The few times he had to resort to using an overpowered {{GMPC}} were done to hastily [[{{Railroading}} put the plot back on the rails]].
* ''Webcomic/TheNoob'' has the MMORPG version, in which the {{Jerkass}} head developer plays a character. And cheats to try and win contests.
* Webcomic/DarthsAndDroids uses this trope when the the regular GM can't make it to the session, and Pete takes over while still playing R2-D2, during the battledroid factory sequence. During the battle, he decides R2-D2 has rocket thrusters, which in the movie, pretty much allowed Artoo to save the day.
** It otherwise averts the trope as the GM has had several {{NPC}}s travel with the party but none of them start behaving like {{PC}}s until a player needs a new character and takes over one of them (Sally does this a lot.)
* Eluamous Nailo in UnforgottenRealms.
* The ''GlobalGuardiansPBEMUniverse'' played with this. While there were loads of [=GMPCs=], they were always characters being run in another [=GMs=] campaign.
* While not quite a fit in this section, the MSFHighForum has a few of these. Mitchell, current head GM, is known for trying to make sure his stay out of the fight, especially at climaxes. For instance, Michelle was busy fighting her evil twin in an ultimately irrelevant battle (And lost), and includes one in his planned Mahou Galaxy adventure, and Legion-based online game.
* In ''Webcomic/OnePieceGrandLine3Point5'', it's revealed near the end of the Syrup Village arc that the GM designed one back when the group consisted of just Luke and Cory. Their old GM [[KillerGameMaster DM]] is surprised when she learns this, as she knows Cory [[BerserkButton especially hates]] [=GMPCs=].

!!!Rare Film Example
* Sir Osric in ''Film/TheGamers: Dorkness Rising''.

!!!Video Game Example
* In the D&D-themed ''Videogame/{{Borderlands 2}}'' DLC ''Tiny Tina's Assault on Dragon Keep'', White Knight Roland serves this role, often appearing in the story just because Tina says so. The other players aren't very happy about this, partly because he's more or less a plot device and because [[spoiler:he's a clear sign that Tina is in denial of the real Roland's death. However, the ending shows that his character is meant to be a tribute to Roland, ultimately having a better fate than his ignoble death at the hands of Handsome Jack.]]

!!!Anime Example
* A major plot twist in LightNovel/SwordArtOnline is that [[spoiler:Kayaba Akihiko, the BigBad who trapped everyone in TheMostDangerousVideoGame, was actually Heathcliff, leader of the Knights of the Blood guild. Kirito, having wondered where Kayaba had been for the last two years of the game, partially deduced his identity when he realized Heathcliff was in too good a condition after what should have been an exhausting battle for even a high-level player. The other key realization was, as Kirito put it, "Something any kid knows. There's nothing as boring as watching someone else play an RPG."]]