Gene Coon wrote mainly for television. His writing credits included Dragnet, Bonanza, Zorro and The Wild Wild West, as well as the premier episode of McHale's Navy. He also became a producer for The Wild Wild West and later became a producer and writer for Star Trek. He joined Star Trek in the middle of the first season, and left in the middle of the second season. He continued to contribute scripts for the third season, under the pseudonym "Lee Cronin", as he was under contract to Universal Studios at the time and was not, technically, supposed to be working for Paramount as well.
His credited creations for Star Trek include the Klingons (in "Errand of Mercy"), Khan Noonian Singh (in "Space Seed") and the Prime Directive. Since he also had the position of doing rewrites for scripts, his work touches many more episodes. He also mentored the young David Gerrold, helping him to write the episode "The Trouble With Tribbles".
Following Star Trek, Coon went on to produce the Universal Studios series It Takes a Thief, starring Robert Wagner, and to write for Kung Fu and The Streets of San Francisco. Coon was known as one of the fastest writers in Hollywood, and it wasn't unusual for him to rewrite a script over a weekend for shooting on the Monday. He had a wonderful, dry sense of humour, as reflected in his two novels, Meanwhile Back At The Front and The Short End (published in 1964 about the Korean War). Coon was also lucky enough to be reunited with the love of his life in time for them to spend his last years together.
He died of lung cancer in 1973.