Ellison moved to California in 1962, and subsequently began to sell his writing to Hollywood.
He co-wrote the screenplay for The Oscar (1966), starring Stephen Boyd and Elke Sommer.
Ellison also sold scripts to many television shows: The Loretta Young Show (using the name Harlan Ellis),The Flying Nun, Burke's Law, Route 66, The Outer Limits, Star Trek, The Man from U.N.C.L.E., Cimarron Strip, and The Alfred Hitchcock Hour.

Ellison's screenplay for the Star Trek episode "The City on the Edge of Forever" has been considered the best of the 79 episodes in the series.

In 1965, he participated in the Selma to Montgomery marches led by Martin Luther King, Jr.
In 1966, in an article that Esquire magazine would later name as the best magazine piece ever written, the journalist Gay Talese wrote about the goings-on around Frank Sinatra.
The article, entitled "Frank Sinatra Has a Cold", briefly describes a clash between the young Harlan Ellison and Frank Sinatra, when the crooner took exception to Ellison's boots during a billiards game.

Ellison was hired as a writer for Walt Disney Studios, but was fired on his first day after Roy O. Disney overheard him in the studio commissary joking about making a pornographic animated film featuring Disney characters.

Ellison continued to publish short fiction and nonfiction pieces in various publications, including some of his best known stories. "'
Repent, Harlequin!'
Said the Ticktockman" (1965) is a celebration of civil disobedience against repressive authority. "
I Have No Mouth, and I Must Scream" (1967) is an allegory of Hell, where five humans are tormented by an all-knowing computer throughout eternity.
The story was the basis of a 1995 computer game; Ellison participated in the game's design and provided the voice of the god-computer AM.
Another story, "A Boy and His Dog", examines the nature of friendship and love in a violent, post-apocalyptic world and was made into the 1975 film of the same name, starring Don Johnson.

Ellison served as creative consultant to the 1980s version of The Twilight Zone science fiction TV series and Babylon 5.
As a member of the Screen Actors Guild (SAG), he had voice-over credits for shows, including The Pirates of Dark Water, Mother Goose and Grimm, Space Cases, Phantom 2040, and Babylon 5, as well as making an onscreen appearance in the Babylon 5 episode "The Face of the Enemy".

Ellison's short story "The Man Who Rowed Christopher Columbus Ashore" (1992) was selected for inclusion in the 1993 edition of The Best American Short Stories.

In 2014 Ellison made a guest appearance on the album Finding Love in Hell by the stoner metal band Leaving Babylon, reading his piece "The Silence" (originally published in Mind Fields) as an introduction to the song "Dead to Me."

Ellison's official website, harlanellison.com, was launched in 1995 as a fan page; for several years, Ellison was a regular poster in its discussion forum.
Ellison moved to California in 1962, and subsequently began to sell his writing to Hollywood. He co-wrote the screenplay for The Oscar (1966), starring Stephen Boyd and Elke Sommer. Ellison also sold scripts to many television shows: The Loretta Young Show (using the name Harlan Ellis),The Flying Nun, Burke's Law, Route 66, The Outer Limits, Star Trek, The Man from U.N.C.L.E., Cimarron Strip, and The Alfred Hitchcock Hour.
Ellison's screenplay for the Star Trek episode "The City on the Edge of Forever" has been considered the best of the 79 episodes in the series.
In 1965, he participated in the Selma to Montgomery marches led by Martin Luther King, Jr.
In 1966, in an article that Esquire magazine would later name as the best magazine piece ever written, the journalist Gay Talese wrote about the goings-on around Frank Sinatra. The article, entitled "Frank Sinatra Has a Cold", briefly describes a clash between the young Harlan Ellison and Frank Sinatra, when the crooner took exception to Ellison's boots during a billiards game.
Ellison was hired as a writer for Walt Disney Studios, but was fired on his first day after Roy O. Disney overheard him in the studio commissary joking about making a pornographic animated film featuring Disney characters.
Ellison continued to publish short fiction and nonfiction pieces in various publications, including some of his best known stories. "'Repent, Harlequin!' Said the Ticktockman" (1965) is a celebration of civil disobedience against repressive authority. "I Have No Mouth, and I Must Scream" (1967) is an allegory of Hell, where five humans are tormented by an all-knowing computer throughout eternity. The story was the basis of a 1995 computer game; Ellison participated in the game's design and provided the voice of the god-computer AM. Another story, "A Boy and His Dog", examines the nature of friendship and love in a violent, post-apocalyptic world and was made into the 1975 film of the same name, starring Don Johnson.
Ellison served as creative consultant to the 1980s version of The Twilight Zone science fiction TV series and Babylon 5. As a member of the Screen Actors Guild (SAG), he had voice-over credits for shows, including The Pirates of Dark Water, Mother Goose and Grimm, Space Cases, Phantom 2040, and Babylon 5, as well as making an onscreen appearance in the Babylon 5 episode "The Face of the Enemy".
Ellison's short story "The Man Who Rowed Christopher Columbus Ashore" (1992) was selected for inclusion in the 1993 edition of The Best American Short Stories.
In 2014 Ellison made a guest appearance on the album Finding Love in Hell by the stoner metal band Leaving Babylon, reading his piece "The Silence" (originally published in Mind Fields) as an introduction to the song "Dead to Me."
Ellison's official website, harlanellison.com, was launched in 1995 as a fan page; for several years, Ellison was a regular poster in its discussion forum.
Harlan Ellison