Game Master (GM)
Also known as: Dungeon Master, DM, Storyteller, ST, Keeper, Referee, MC, Judge
Definition
The player who runs the game: describing the world, playing NPCs, presenting challenges, and adjudicating rules. The GM facilitates the story but doesn't 'win' or 'lose.'
How it works in different systems
D&D 5e: Dungeon Master (DM) - traditional authority figure, creates dungeons and adventures.
Vampire V5: Storyteller (ST) - emphasis on collaborative narrative over challenge.
Call of Cthulhu 7e: Keeper (of Arcane Lore) - focuses on mystery and horror atmosphere.
Powered by the Apocalypse: Master of Ceremonies (MC) - follows principles, plays to find out what happens.
Example
“GM: 'You enter the abandoned warehouse. Moonlight streams through broken windows, illuminating dusty crates. What do you do?' Player: 'I want to search for traps.' GM: 'Roll Investigation.'”
Origin & History
Dungeon Master originated with D&D (1974). Game Master became the generic term. Different games use different titles reflecting their themes.