Stephen R. Marsh is an American game designer known for his contributions to early editions of TSR’s Dungeons & Dragons role-playing game. Stephen has been a brilliant designer “in the shadows” since the beginnings.
Stephen borrowed a copy of the published D&D rules from classmate Sandy Petersen and after reading the rules of this new game, he began to correspond with D&D co-creator Gary Gygax. He sent his own vision of an elemental plane of water to Gygax, who changed it into a system for underwater combat encounters, and subsequently incorporated it into the Blackmoor supplement published in 1975. Stephen’s material introduced new aquatic creatures, including the Sahuagin, Ixitchitchitl and Catoblepas. He also suggested the Mystic, a new character class who could teleport to various planes of existence via mental powers. The character class concept was not published although mental abilities of the mystic were altered and then published in the Eldritch Wizardry supplement the following year as the first psionic powers for D&D. Some of the creatures he created for the supplements to D&D in 1975 and The Strategic Review have been included in every subsequent edition of the game.
Stephen R. Marsh was credited in essays by E. Gary Gygax, The Strategic Review and in The Dragon as well as credited with «Special Thanks» on the credits page «for Suggestions and Contributions».
He convinced Gygax to add a Good and Evil axis to D&D’s character alignment system when he was developing Advanced Dungeons & Dragons. Originally, characters could only be Lawful, Chaotic or Neutral so adding a second axis, the number of possible alignments based on combinations of Law, Chaos, Good, Evil and Neutral.
The aquatic creature creations were converted to the new AD&D game system by Gary Gygax for use in the Monster Manual in 1977, where Gygax credited Marsh «for devising the creatures for undersea encounters which originally appeared in BLACKMOOR, as I have radically altered them herein.» All of these creatures have been incorporated into each new edition of D&D. Later, he convinced Gygax that a rule book about travel to different planes would be worthwhile. They started to develop a new AD&D rulebook, The Planes of Existence, but just as the manuscript was being readied for a 1986 publication date, Gygax was forced out of TSR, all Gygax-related projects were immediately shelved, and the book was never published. The rules for Starstrands, an interplane that connected various prime material planes, with many monsters, mini-dungeons, and other material, were among the papers from Gary’s office that were burned.
He worked during a summer at TSR, where he was the writer on the Dungeons & Dragons Expert Set. He also reviewed and approved licensed Judges Guild products, and helped create the minigame Saga.
Several previously unpublished Lovecraft-inspired monsters created by Stephen for his home campaign were published in Monsters of Myth, in 2008.
He goes NTRPG Con every year and has been showing examples of plane related play each year.
Stephen is one of the biggest authors in roleplaying games.