[1] A gay man, Herlihy became a close friend of playwright Tennessee Williams, who served as his mentor.

Apart from Key West, the primary home of Herlihy was in the Silver Lake district of Los Angeles.

Plays he wrote include Streetlight Sonata (1950), Moon in Capricorn (1953), and Blue Denim (produced on Broadway in 1958).

[1] Herlihy appeared as a guest star in "A Bunch of Lonely Pagliaccis," a 1962 episode of the TV series Route 66.

Herlihy also acted in Edward Albee's play The Zoo Story in 1963 in Boston and Paris,[1] and in the 1981 film Four Friends directed by Arthur Penn.