Robert Clarke

 played Prince Horst Hapsburg in the Tabitha episode, Tabitha's Weighty Problem (1977).

Biography
Robert Irby Clarke was an American actor and writer. His acting roles ran the gamut from "The Man from Planet X" (1951) and "The Astounding She-Monster" (1957) to "Band of Angels" (1957) starring Clark Gable.

Clarke originally planned to go into the military, but an asthma condition kept him out of service. He attended The University of Oklahoma and then The University of Wisconsin before moving on to Hollywood in 1942.

He signed a contract with RKO where his first movie was "The Falcon in Hollywood" (1944). After that, he did a number of small, and some uncredited, roles until he made his mark as a star in "B" movies.

Clarke married Alyce King of the singing King Sisters in 1956 and began appearing with "The King Family" on tours in 1965. He and Alyce were married until her death in 1996.

Robert Clarke also tried his hand at writing, and his autobiography "To 'B' or Not to 'B': A Film Actor's Odyssey" was published in 1996. His last acting role was in the "The Naked Monster" (2005).

Source
Brenda N. Robert I. Clarke memorial, Findagrave.com, June 22, 2005. Retrieved on March 2, 2020.