Along with Majel Barrett, Joseph Ruskin and Clint Howard, he is one of only four actors to appear in both "Star Trek" (1966) and "Star Trek: Enterprise" (2001). Of these, he is the only one who did not also appear in "Star Trek: Deep Space Nine" (1993).
He made a total of eleven guest appearances in "Mission: Impossible" (1966), more than any other guest star.