His film work includes The Competition, Outland, Up the Creek and Star Trek III: The Search for Spock, as well as a minor (but crucial) part, as a cynical hitman, in the earlier Point Blank. Sikking's film career started in 1955. Sikking starred in the 1992 Fox Network TV movie Doing Time on Maple Drive. He has made guest appearances on many TV series including Perry Mason, Rawhide, Bonanza, The Outer Limits, General Hospital, The Rockford Files, The Bob Newhart Show, Hogan's Heroes, Rich Man, Poor Man Book II, Hunter and Batman Beyond.
Sikking was born in Los Angeles. His mother, Sue Sikking (née Paxton), was a founder of Santa Monica's Unity-by-the-Sea Church. Sikking graduated from UCLA in 1959 and attended the University of Hawaii. He has two brothers, Tom and Art, and a sister, Joy. He is married to Florine Sikking, a cookbook author. They live in the Brentwood section of Los Angeles.