Greg Costikyan, also known as Designer X, is an American game designer and science-fiction writer. Costikyan's career spans nearly all extant genres of gaming, including hex-based wargames, role-playing games, board games, card games, computer games, online games and mobile games. Several of his games have won Origins Awards. Costikyan was the game designer for the original version of Star Wars: The Roleplaying Game, and is credited under "original design" for its subsequent editions.
Greg Costikyan is credited on the following West End Games books:
- Star Wars: The Roleplaying Game (credited with "design")
- The Star Wars Sourcebook (credited with "additional development")
- Star Wars: The Roleplaying Game, Second Edition (credited with "original design")
- Tales of the Jedi Companion (credited with "Original Force Power Design")
- The Jedi Academy Sourcebook (credited, along with Greg Gorden, with "Additional Design" for the Force powers "Contort/escape," "Force of will," and "Shift sense")
- Star Wars: The Roleplaying Game, Second Edition, Revised and Expanded (credited with "original design")
His work on the first edition of Star Wars: The Roleplaying Game was recognized with an Origins Award for Best Role-playing Rules of 1987.
- The Secrets of Star Wars: Shadows of the Empire