Oscar-winner Edmond O'Brien was one of the most respected character actors in American cinema, from his heyday of the mid-1940s through the late 1960s. Born on September 10, 1915, in the New York City borough of Brooklyn, O'Brien learned the craft of performance as a magician, reportedly tutored by neighbor Harry Houdini. He took part in student theatrics in high school and majored in drama at Fordham University, dropping out after six months. He made his Broadway debut at the age of 21 in 1936 and, later that year, played "The Gravedigger" in the great Shakespearean actor John Gielgud's legendary production of "Hamlet". Four years later, he would play 'Mercutio' to the 'Romeo' of another legendary Shakespearean, Laurence Olivier, in Olivier's 1940 Brodway production of "Romeo & Juliet".

O'Brien worked with another magician, Orson Welles, in the Mercury Theater's production of "Julius Caesar", appearing as 'Mark Antony'. He would later play 'Casca' in Joseph L. Mankiewicz's film of the play, Julius Caesar (1953).

Although it has been stated that he made his debut as an uncredited extra in the 1938 film, Prison Break (1938), the truth is that his stage work impressed RKO boss Pandro S. Berman, who brought him to Hollywood to appear in the plum supporting part of 'Gringoire' in The Hunchback of Notre Dame (1939), which starred Charles Laughton in the title role. After returning from his wartime service with the Army Air Force, O'Brien built up a distinguished career as a supporting actor in A-list films, and as an occasional character lead, such as in D.O.A. (1949).

O'Brien won an Academy Award for Best Supporting Actor for his role in The Barefoot Contessa (1954) and also received a Best Supporting Actor Oscar nomination for his role as a drunken senator who ferrets out an attempted coup d'etat in Seven Days in May (1964). He also appeared as crusty old-timer 'Freddy Sykes', who antagonizes Ben Johnson's character 'Tector Gorch' in director Sam Peckinpah's classic Western, The Wild Bunch (1969). Increasingly, O'Brien appeared on television in the 1960s and '70s, but managed a turn in his old boss Welles' unfinished film, The Other Side of the Wind (2018).

He married and divorced actresses Nancy Kelly and Olga San Juan, the latter being the mother of his three children, including actors Maria O'Brien and Brendan O'Brien. He died in May of 1985 in Inglewood, California, of Alzheimer's Disease and was interred in Holy Cross Cemetery in Culver City, California.