Actor. The only actor to win three Best Supporting Actor Oscar awards, he was one of the most successful character actors in American film. While attending college in Cambridge, Massachusetts, studying to be an engineer, Brennan became interested in theatre and appeared in school plays. He worked some in vaudeville and also held various jobs such as a bank clerk and lumberjack. He toured with small musical comedy companies before entering the military in 1917. Serving in the U.S. Army as a private with the 101st Field Artillery Regiment during World War I (WWI), he served in France for two years. While serving in the military, he suffered an injury to his vocal cords due to mustard gas exposure. The injury gave him a distinct, high-pitched voice. After World War I, he went to Guatemala to raise pineapples, and then moved to Los Angeles, California, where he speculated in real estate. He entered motion pictures as an extra beginning in 1923, then did some work as a stuntman. With his wiry frame, thinning hair, lost teeth and weary expression, which made him look older than he really was, he eventually landed supporting roles in numerous features and short subjects between 1927 and 1938. The first of his three Oscars was for his role in "Come and Get It" (1936), which was the first Best Supporting Oscar ever awarded. He would win the award again in 1938 in "Kentucky," and again in 1940 in a particularly vivid performance as Judge Roy Bean in "The Westerner." He was also nominated for his performance in "Sergeant York" (1941). He displayed his range in dozens of roles, most effectively in Westerns. He appeared with John Wayne in "Red River" (1948) and "Rio Bravo," (1959) and was a memorable Old Man Clanton in "My Darling Clementine" (1946). Among his more than 100 feature films were "The Adventures of Tom Sawyer" (1938), "The Story of Vernon and Irene Castle" (1939), "Meet John Doe"(1941), "The Pride of the Yankees" (1942), "To Have and Have Not" (1944), "Bad Day at Black Rock" (1955), "How the West Was Won" (1962), and "The Gnome-Mobile" (1967). He also starred in three TV series, including "The Real McCoys," which ran for six seasons, "Tycoon" and "The Guns of Will Sonnett." He even had a hit record, the spoken/sung, "Old Rivers," which first charted on April 7, 1962, spent 11 weeks on the Billboard charts, and peaked at number 5. This lead to several albums of similar material and three other top 100 singles.