Harlan Ellison, one of the most influential sci-fi writers of the twentieth century, passed away today in his sleep. He was 84 years old.

Christine Valada, the widow of the late Len Wein and a friend of Harlan and his wife Susan, officially announced the author's passing on Twitter.

"Susan Ellison has asked me to announce the passing of writer Harlan Ellison, in his sleep, earlier today," Valada wrote. “For a brief time I was here, and for a brief time, I mattered.”—HE, 1934-2018. Arrangements for a celebration of his life are pending.

"If there’s an afterlife, Harlan Ellison and @LenWein will have a hell of a time. Thanks for the laughter."

Ellison's career as a writer began in the late '40s, when he was still a teenager, selling several stories to the Cleveland News. In the early '50s, he sold a story to EC Comics before writing ever 100 short stories a two year span. After a brief career in the Army in the late-'50s, Ellison moved to Hollywood in the '60s where he established himself as a scriptwriter for both movies and television. Over the decades, he wrote a number of acclaimed scripts, including "The City on the Edge of Forever," considered by many to be the greatest episode of the original Star Trek series.

Ellison was known not only for his contributions to the world of sci-fi and comic books, but as an outspoken, often brutally honest critic. As acclaimed as he was as a writer, the stories about his personal life were often just as colorful and interesting, the most well known of which perhaps being the time he was hired to write for Walt Disney Studios, only to be fired on his first day after being overheard joking about making an animated porno starring Disney's iconic characters.

Ellison is survived by his wife Susan.