King was cast in numerous westerns and is particularly known for his role in the 1951 film adaptation of Tennessee Williams' A Streetcar Named Desire, starring Vivien Leigh (whom his character kisses). Prior to that, he had appeared in the original stage production, a performance that was lauded by drama critic Harold Hobson. Other noteworthy film credits included roles in Cast a Long Shadow (1959), King Rat (1965), Planet of the Apes (1968), Finian's Rainbow (1968) and Invasion of the Bee Girls (1973). In 1974, he played U.S. Senator Richard B. Russell, Jr., of Georgia in the ABC television film, The Missiles of October, a dramatization of the Cuban Missile Crisis of 1962. He appeared in the television series Johnny Jupiter and was Steve McQueen's partner for a season of Wanted Dead or Alive.