Non-player character

Refers to any sentient creature whom one encounters in IF. NPCs include robots, animals, and people. The term is also sometimes (more rarely and perhaps incorrectly) used to refer to characters who are referred to in the text but not directly encountered. [ES]

Of course, this becomes more complicated in games where the player controls different characters throughout the course of the game - the original PC will become an NPC and an NPC becomes the PC.

Additionally: The line between non-player character and simple object can be hard to draw. There is a gradation between a man on a bench who will only answer questions, a computer that will answer questions, and an encyclopedia that the player can look things up in. These have the exact same function in the game, but the man will be considered a non-player character, the encyclopedia will not be, and the computer may be considered either. -- DavidThornley - 09 Sep 2002