American writer of short stories, novels, essays, and television and film scripts; he is best known for his science-fiction writing and editing.

Ellison briefly attended Ohio State University and later became a prolific contributor of science fiction, crime and sex fiction, and true confessions to genre magazines. After serving in the U.S. Army (1957–1959), he edited Rogue magazine from 1959 to 1960 and founded Regency Books press in 1960 before becoming a successful television scriptwriter.

Ellison's reputation as an important science-fiction writer rests on such short stories as “ ‘Repent, Harlequin!' Said the Ticktockman” (1965), “A Boy and His Dog” (1969), and several others, including those in the collections I Have No Mouth and I Must Scream (1967) and The Beast That Shouted Love at the Heart of the World (1969). As an editor he published several important anthologies; for each of the stories he commissioned for Dangerous Visions (1967) and Again, Dangerous Visions (1972), he added a personal introductory essay that reveals as much about himself as it does about the work in question. Among Ellison's own collections are Deathbird Stories: A Pantheon of Modern Gods (1975), All the Lies That Are My Life (1980), The Harlan Ellison Hornbook (1990), Mefisto in Onyx (1993), and Slippage: Precariously Poised, Previously Uncollected Stories (1997). Ellison's most influential short stories and essays were collected in The Essential Ellison: A 50-Year Retrospective (2001). He also wrote several books of television and movie criticism and numerous screenplays and teleplays for series such as Star Trek, The Twilight Zone, and Babylon 5. Ellison was the subject of a documentary, Dreams with Sharp Teeth, that was released in 2008, after more than 25 years of filming.