Tall, imposing American actor Frank Shannon made his screen debut in 1913's The Prisoner of Zenda. Shannon then returned to the stage until beckoned back to Hollywood in the early '30s. Though mostly confined to bit roles until his retirement in 1943, Shannon managed to play a few substantial supporting parts, including Captain McTavish in Warner Bros.' Torchy Blaine series. Frank Shannon is most fondly remembered as the brilliant, bearded Dr. Zarkov in the three Flash Gordon serials produced by Universal between 1936 and 1940. ~ Hal Erickson, All Movie Guide