(written from a Production point of view)
David Gerrold (born 24 January 1944; age 71) (real name Jerrold David Friedman) is a screenwriter and science fiction author, who wrote episodes of original series' and animated series', and also worked as a story editor on Star Trek: The Next Generation. He left near the end of that series' first season in a dispute with Gene Roddenberry.
Gerrold wrote the scripts for the original series' "The Trouble with Tribbles" and its sequel, the animated series' "More Tribbles, More Troubles", as well as The Animated Series episode "Bem". The first of these was nominated for a Hugo Award. He provided the story, along with Oliver Crawford, for TOS: "The Cloud Minders". He also provided an uncredited rewrite of the final draft of the script for TOS: "I, Mudd".
Before his script outline that became "The Trouble With Tribbles" was bought by Star Trek producers, Gerrold (a recent college graduate), early in 1967, submitted a sixty-page outline for a two-part episode, "Tomorrow Was Yesterday". After that outline was responded to, positive for its quality, negative for its usefulness to the series, Gerrold was invited to submit some script outlines suitable for the program's budget. Gerrold submitted five outlines, including "A Fuzzy Thing Happened To Me..." (which became Tribbles), "The Protracted Man", "Bandi", and two others with titles Gerrold did not recall some years later. One of the others involved Kirk playing a chess game with his crew as chess pieces, the other involved a spaceship-destroying machine, an idea he noted as eerily similar to Norman Spinrad's story "The Doomsday Machine" that was produced for the same season. Gerrold also came up with both "More Tribbles, More Troubles" and "Bem" as story ideas for the third season, however producer Fred Freiberger refused to buy either of them. They were re-developed and produced for the The Animated Series five years later.
A caricature of Gerrold was included in "More Tribbles, More Troubles" as an in-joke. According to the novelization of the episode by Alan Dean Foster, this individual was named "Hacker," a name which Gerrold later found insulting.
In 1987, Gerrold was hired as a story editor on Star Trek: The Next Generation, in which capacity he wrote many elements in the Writers' Bible for the series. He left the show near the end of the first season, mainly because of the dispute over his controversial script, "Blood and Fire". The story, which was basically an allegory of AIDS, and involved allegedly homosexual characters, was initially scrapped by the producers. It was re-written by Herb Wright as "Blood and Ice", removing the gay characters, but it still remained unproduced. Gerrold received credit as Program Consultant for the early part of the first season, from "The Naked Now" to "Lonely Among Us".
In addition to writing, he provided the voice for Em/3/Green in the TAS episode "The Jihad", and was an extra in Star Trek: The Motion Picture and the Star Trek: Deep Space Nine episode "Trials and Tribble-ations". He originally wanted to appear in a smaller role in "The Trouble with Tribbles" (some sources say he wrote the part of Ensign Freeman for himself), but it never came to fruition.
Gerrold's son Sean, who was twelve at the time of the filming of "Trials and Tribble-ations", joined his father on the DS9 set. Sean asked his father where the Enterprise crew kept their money (a question which Gerrold himself had once asked Gene L. Coon) and expressed disappointment that James T. Kirk and Spock were not actually there. (Trials and Tribble-ations introduction)
Gerrold wrote the novelization of the TNG pilot, Encounter at Farpoint, and the Original Series novel, The Galactic Whirlpool, which was developed from his the aforementioned "Tomorrow Was Yesterday" outline. He also wrote the foreword of the "Trials and Tribble-ations" novelization and the introduction of the Constellations anthology. Outside fiction, Gerrold wrote The World of Star Trek, a behind-the-scenes reference and interview book, and The Trouble with Tribbles, detailing his experiences in the production of the titular episode, both in 1973.
Outside Star Trek, he wrote the "Star Wolf" trilogy, using some scripts not used for Star Trek, which enthusiasts sometimes call "Star Trek like it should have been"; apart from his Star Trek novels and the tribbles episode, his most famed work may be "The War against the Chtorr", in which he describes a biological invasion of planet Earth by a hostile ecology. He also wrote the novelization of the 1973 film Battle for the Planet of the Apes, which featured Paul Williams, France Nuyen, music by Leonard Rosenman and cinematography by Richard H. Kline. Gerrold himself appeared in the movie in a small cameo role, as a dead ape in a battle scene.
His novel The Martian Child was the source for the 2007 comedy drama film Martian Child, in which an author adopted a boy after his fiancée passed away. The story is semi-biographical – Gerrold himself adopted a boy in 1992. The main character, played by actor John Cusack, is also named David in this film. Gerrold served also as executive producer for this production and Star Trek stuntman Lauro Chartrand appeared in this film.
More recently, Gerrold wrote and directed the fan-made internet series Star Trek: New Voyages episode "Blood and Fire" (2007), which features James Cawley, John Carrigan, Denise Crosby, and Bill Blair. It is a re-working of his "Star Wolf" book Blood and Fire (itself, a re-working of the aforementioned story he originally wrote for TNG). Another episode, a further sequel to "The Trouble with Tribbles", is planned.
Although Gerrold had for many years a contentious relationship with both Star Trek and Gene Roddenberry, he has reconciled himself to his association with the show and speaks of his experiences fondly. 
The 2009 DVD box release Star Trek: Original Motion Picture Collection featured a reunion of fan extras in the "Special Star Trek Reunion", including Gerrold, Christopher Doohan, Bjo Trimble, Jo Ann Nolan, and Fred Bronson chatting on the same soundstage used for the rec deck scene. 
Star Trek appearances
Star Trek books
- The World of Star Trek (1973)
- The Trouble with Tribbles (1973) - Details the production of the classic Star Trek episode
- Constellations (2006) - Introduction
- Boarding the Enterprise: Transporters, Tribbles, And the Vulcan Death Grip in Gene Roddenberry's Star Trek (2006) with Robert J. Sawyer
Outside Star Trek
War Against the Chtorr
- A Matter for Men (1983)
- A Day for Damnation (1985)
- A Rage For Revenge (1989)
- A Season for Slaughter (1993)
- A Method For Madness (in progress as of 2006)
- A Time For Treason (under contract to write)
- A Case For Courage (planned)
- also: "GURPS Chtorr"
- Voyage of the Star Wolf
- The Middle of Nowhere
- Blood and Fire
- "Believers" (script, Season 1, 1994)
- The Flying Sorcerers (with Larry Niven)
- When H.A.R.L.I.E. was One
- Space Skimmer
- Yesterday's Children
- The Man Who Folded Himself
- Moonstar Odyssey
- The Martian Child
- Jumping Off The Planet
- Bouncing Off The Moon
- Leaping To The Stars