Larry DiTillio (1948-2019) was an American screenwriter and game designer. He wrote seventeen episodes of He-Man and the Masters of the Universe, more than anyone else on the show, then built the series bible for its spin-off She-Ra: Princess of Power and named most of its characters. With J. Michael Straczynski he went on to Babylon 5, where he was story editor for the first season and executive story editor for the second, and wrote seven episodes. For tabletop players his name belongs to Masks of Nyarlathotep, the globe-spanning campaign he wrote for Chaosium's Call of Cthulhu in 1984, still reissued and widely held to be among the finest scenarios written for any role-playing game.