A Game Master (simplify as GM) is a person who acts as an organizer, officiant for questions 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 game master in the ZRPG Series is to weave the other participants' player-character stories together, control the non-player aspects of the game, create environments in which the players can interact, and to solve any player disputes.

A good gamemaster draws the players into the adventure, making it enjoyable for everyone. Good gamemasters have quick minds, sharp wits, and rich imaginations. Gamemasters must also maintain game balance: hideously overpowered monsters or players are no fun. Multiple game masters often work side by side on a single ZRPG to lessen the workload of managing the game. These assistant game masters are known as Co-GM's.