Along with Majel Barrett, Clint Howard and Jack Donner, he is one of only four actors to appear in both "Star Trek" (1966) and "Star Trek: Enterprise" (2001).
He has had roles in four different "Star Trek" series: "Star Trek" (1966), "Star Trek: Deep Space Nine" (1993), "Star Trek: Voyager" (1995) and "Star Trek: Enterprise" (2001). Besides Majel Barrett, who has appeared all five "Star Trek" series, he is the only actor to appear in four. Moreover, since Barrett only provided voice overs in the latter two series, he is the only actor to appear on screen in four out of five.
Is one of only 32 actors or actresses to have starred in both the original "Star Trek" (1966) (up to and including Star Trek: Insurrection (1998)) and then in three of the four spin off TV series.