Mack Swain was an American actor and vaudevillian, prolific throughout the 1910s, 1920s and 1930s.
Born Moroni Swain to Robert Henry Swain and Mary Ingeborg Jensen in Salt Lake City, Utah, he worked in vaudeville before starting in silent film at Keystone Studios under Mack Sennett. While with Keystone, he was teamed up with Chester Conklin to make a series of comedy films. With Swain as "Ambrose" and Conklin as the grand mustachioed "Walrus", they performed these roles in several films including "The Battle of Ambrose and Walrus" and "Love, Speed and Thrills," both made in 1915. Besides these comedies, the two appeared together in a variety of other films, twenty-six all told.
In 1921, Swain began working with Charlie Chaplin at First National, appearing in "The Idle Class", "Pay Day" and "The Pilgrim". He is also remembered for his role as Big Jim McKay in the 1925 film The Gold Rush, for United Artists, written by and starring Chaplin.