Although he came to be called "Hollywood's Irishman in Residence"--and, along with good friends James Cagney, Allen Jenkins, Frank McHugh and a few others were called "The Irish Mafia"--and he often played Irish immigrants, Pat O'Brien was US-born and -bred. As a young boy the devoutly Roman Catholic O'Brien considered entering the seminary to study for the priesthood, but although he often played a Father, Monsignor or Bishop, he never actually followed through and entered the seminary. And although never a policeman, in movies he often wore the cop's badge and, although in real life he had no discernible Irish accent, he could pour on the "brogue" when the role called for it.
Pat O'Brien excelled in roles as beneficent men but could also give convincing performances as wise guys or con artists. He was a most popular film star during the 1930s and 1940s. Over almost five decades, he co-starred in nine films with Cagney, including his own screen swansong, Ragtime (1981).
