This Island Earth (1955)
I always liked this movie. It starred Jeff Morrow as Exeter, Faith Domergue as Dr. Ruth Adams, Rex Reason as Dr. Cal Meachum, and Russell Johnson as Steve Carlson. Russell Johnson went on to play "the Professor" on Gilligan's Island. This was directed by Joseph Newman who also directed on TV series such as The Big Valley, The Alfred Hitchcock Hour, and The Twilight Zone.