World builder. Storyteller. Rules arbiter. Plot writer. Director. Facilitator. Actor. Entertainer. Improv expert. Enemy. Caretaker. Group manager. Event host. The game master (GM) fulfills many tasks, takes on many roles, too numerous to count, and thus, has many faces – and also many names. In TRPGs, usually one single GM juggles all the aspects of this role. In larps, we literarily can encounter a thousand faces if we consider mass conventions. Plot-GMs and battle-GMs have direct player contact in mainstream larps, with plot writers and logistics managers working in the background but with equal importance. Many game masters – or storytellers, dungeon masters, keepers – and organizers prepare and host play as a hobby. Increasingly, we encounter professional GMs, for example, in TRPG cafés in Japan or as educational larpwrights working for an NPO. The thousand faces become ten thousand. Contrastingly, some games follow a trend of GM-less play, eschewing this role completely. Still, how individual GMs take on their role or how the game dislocates the game mastering onto rules or the other players, crucially affects the entertainment value of TRPGs and larps or how they can become vehicles to transport messages and learning goals. We believe the time is right to put the GM into the spotlight of academic and practical investigations. Thus, the JARPS 2022 special issue deals with all aspects of game mastering, focusing on this particular role, but being open also to questions of larp organization or plot writing.