gamemaster

A gamemaster (GM), also known as a game master, game manager, game moderator, referee, storyteller, or master of ceremonies, is a person who acts as a facilitator, organizer, officiant regarding rules, arbitrator, and moderator for a multiplayer role-playing game. The act performed by a gamemaster is sometimes referred to as "gamemastering" or simply "GM-ing."

The role of a GM in a traditional tabletop role-playing game (TTRPG) is to weave together the other participants' player characters (PCs) stories, control the non-player characters (NPCs), describe or create environments in which the PCs can interact, and solve any player disputes. This basic role is the same in almost all traditional TTRPGs, with minor differences specific to differing rule sets. However, in some indie role-playing games, the GM role significantly differs from the traditional pattern. For example, in Powered by the Apocalypse systems, the other players assist the GM in creating both the NPCs and the details of the campaign setting.