A non-player character or non-playable character is a fictional character in a role-playing game whose role is generally created and performed by the gamemaster. Non-player characters (or "NPCs") keep the game's fictional world running — from the Friendly Innkeeper in Dungeons & Dragons to a Fixer or Netrunner in a cyberpunk-themed game. Non-player characters are either the allies, bystanders or competitors to the player characters (PCs), the fictional characters whose roles are created and performed by the other players rather than the gamemaster.

NPCs range in importance greatly — the aforementioned Innkeeper may be seen once by the characters, but their arch-nemesis that comes back time and again to foil their plans for an entire campaign is also a NPC — just one with a lot more time and effort put into him by the gamemaster. Technically, every inhabitant of the game's world except the PCs are NPCs, but very few are given any detail by the gamemaster.

In the Champions game (and related games using the Hero System), a character may have a DNPC, or "dependent non-player character." This is a character controlled by the GM, but for which the player character is responsible in some way, and who may be put in harm's way by the PC's choices. Spider-Man's Aunt May would be a good example of a DNPC, if Spider-Man were a Champions character.

There is some discussion as to just how important fully fleshed-out NPCs are in any given RPG, but it's general consensus that the more "real" a NPC feels, the more fun players will have interacting with him in character. Gamemasters should remember that just as a player character has hopes, dreams, and goals, so does every NPC, and player characters getting in the way of them could lead to unfortunate encounters.

There is also debate about how much work a gamemaster should put into a NPC regarding game statistics — some people prefer to have every NPC completely defined, with stats, skills, and gear, while others define only what's necessary and fill in the blanks as they go along. This is often the approach with gamemasters who GM "on the fly."

The term is also used in computer role-playing games to describe entities not under the direct control of players. Nearly always the connotation is that an NPC is allied with, or at least neutral toward, the player, rather than being an enemy. Other times the term NPC is used to denote a game character with relatively sophisticated AI code, no matter whether he is friendly or not.