Stephen R. Marsh

Stephen R. (Steve) Marsh is an American game designer and lawyer best known for his contributions to early editions of TSR's "Dungeons & Dragons" fantasy tabletop role-playing game (RPG). Some of the creatures he created for the original edition of "D&D" in 1975 have been included in every subsequent edition of the game.
Game design career.
Early to mid-1970s: Original D&D.
While attending high school, Marsh began to play military boardgames. His interest led him to attempt to design what would now be called a roleplaying game based on his board games and using "The Golden Bough" as the basis for a magic system. However, he was unable to come up with a satisfactory system until he borrowed a copy of the recently published D&D rules from classmate Sandy Petersen. (Petersen would go on to create the "Call of Cthulhu" RPG in 1981.) After reading the rules of this new game, Marsh began to correspond with D&D co-creator Gary Gygax.
His Catoblepas appeared in the TSR house magazine The Strategic Review and is still in 5th Edition D&D. 
Marsh eventually sent his own vision of an elemental plane of water to Gygax, who incorporated a number of the underwater creatures and magic items into Dave Arneson's "Blackmoor" supplement published in 1975, to expand significantly on Arneson's swamp and oceanic content. Marsh's material introduced several new and soon to be iconic aquatic creatures, including the sahuagin, ixitchitchitl, and Aquatic Elves. Marsh also suggested a new character class, the mystic, that could teleport to various planes of existence via mental powers. Although the character class concept was not published, some of the 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". Marsh was not paid for his creative contributions to either of these rules supplements. Marsh was credited with "Special Thanks" on the credits page "for Suggestions and Contributions".
1977-: Advanced D&D.
Marsh claimed that when Gary Gygax was developing "Advanced Dungeons & Dragons", he convinced Gygax to add a Good and Evil axis to D&D's character alignment system. (Originally, characters could only be Lawful, Chaotic or Neutral. By adding a second axis, the number of possible alignments based on combinations of Law, Chaos, Good, Evil and Neutral grew from three to nine.)
In 1977, most of Marsh's aquatic creature creations were converted to the new AD&D game system by Gary Gygax for use in the "Monster Manual"; in the preface 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 subsequent edition of D&D.
After earning his B.A. (Economics) from California State University-Los Angeles in 1979, Marsh enrolled in law school at Brigham Young University. During the 1980 summer break, he worked at TSR, where he was lead writer on the 1981 version of "Dungeons & Dragons Expert Set". He also reviewed and approved licensed Judges Guild products, and helped create the minigame "Saga", for which he received one royalty payment — the only time he received compensation for creative work other than his salary.
Steve Marsh completed law school and was admitted to the bar in 1982. He continued to correspond with Gygax in the hopes of creating a hardcover book for which he would be paid royalties, and he convinced Gygax that a rule book about travel to different planes would be worthwhile. Together, Marsh and Gygax started to develop a new AD&D rulebook, "The Planes of Existence", which Gygax mentioned in his column in the March 1980 issue of "Dragon". A color cube illustrating how their planes would interface appeared in the May 1983 issue of "Dragon". However, 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.
Recent years.
In 2008, several previously unpublished Lovecraft-inspired monsters created by Marsh for his home campaign were published in "Monsters of Myth", an e-book published by the First Edition Society.
He attends North Texas RPG Con every year and has been demonstrating examples of plane related play each year. For 2015 those who played in his event were given a three hundred page convention module on the plane of shadows. In 2016 Marsh ran a reprise of City of the Revenant and the Planes of Fire and Ice. In 2017 ran 3 scenarios including the City of the Revenant, An OD&D scenario and one other.
Legal career.
Marsh in 1985 became a litigator.
He was first cited in the Code of Federal Regulations circa 1999.