Karl Swenson (July 23, 1908 – October 8, 1978) was an American theatre, radio, film, and television actor. Swenson is remembered for his role as the doomsayer in the diner in Alfred Hitchcock's The Birds (1963) and as the voice of Merlin in Disney's The Sword in the Stone (1963). On television, he had numerous credits in guest roles on various shows, especially Westerns, including episodes of Bonanza, The Virginian, and Gunsmoke. He had a major recurring role as Walnut Grove founder Lars Hanson on Little House on the Prairie (1974 - 1978).

Swenson also had roles in The Prize (1963), Major Dundee (1965), The Sons of Katie Elder (1965), The Cincinnati Kid (1965), Seconds (1966), Hour of the Gun (1967), ...tick...tick...tick... (1970), The Wild Country (1970), Vanishing Point (1971) and Ulzana's Raid (1972).