Born in Dublin, Jack MacGowran worked as an insurance assessor for eight years before becoming an actor with the Abbey Theatre. He made his film debut in John Ford's The Quiet Man (1952). He was also a noted stage actor specialising in works by Sean O'Casey and Samuel Beckett. He appeared in "Waiting For Godot" at the Royal Court Theatre London, and with the Royal Shakespeare Company in "Endgame" at the Aldwych Theatre. He released an LP record, "MacGowran Speaks Beckett", to coincide with Samuel Beckett's 60th birthday. While Jack MacGowran was making The Fearless Vampire Killers (1967), it was suggested by Roman Polanski and Gérard Brach, who wrote the original story for Wonderwall (1968), that he play the part of Professor Collins.
Father of Tara MacGowran.
Shortly after completing his role in The Exorcist (1973), he died in New York (He was appearing as Fluther in "The Plough and the Stars" with Siobhan McKenna at the time.
Won the 1970-71 Obie for Best Performance By an Actor in the off-Broadway play "Beckett".