Non-player character

From RPGnetWiki

A Non-player character (commonly abbreviated as NPC) is a character controlled by the referee (by whatever title he is known). Non-player characters are usually not the protagonists of a game, as that role falls to the player characters. Instead, non-player characters make up all of the other people populating the game's universe. This notably includes any allies the player characters may have as well as the villains they face.

Compare player character.