Jason Bulmahn is an American game designer who has written or contributed to several works.

Jason Bulmahn coordinated the world's largest organized play D&D campaign for the RPGA (Living Greyhawk),[citation needed] and then joined Paizo Publishing as the managing editor of Dragon in 2004.

[2] Within two months of Wizards of the Coast's August 2007 announcement of D&D fourth edition, Bulmahn began working on a new edition of the d20 system that updated and cleaned up the rules, and that he referred to as "a small side project".

[4] The Beta version of the Pathfinder RPG received the gold ENnie award for "best free product or web enhancement" in 2008.

His RPG design credits include the Pathfinder Roleplaying Game Core Rulebook, Bestiary, Ultimate Guides, the Advanced Player's Guide, the Beginner Box, and 2013's Mythic Adventures.