Gregg Palmer - born Donald Van der Maaten — appeared in two Doctor Who television stories: as Gern and Shav in The Tenth Planet and Lieutenant Lucke in The War Games. Thus, he is one of the actors who originated the long-running species of the Cybermen.
As Toby Hadoke and the actor himself have made clear, he is often confused with an American actor who appeared in Star Trek and numerous Western productions. Early in his career, Van der Maaten took the name "Gregg Palmer" because his Dutch name gave the false impression that he couldn't speak fluent English. Unfortunately, British Equity green-lit a name change without thoroughly checking their American counterpart's rosters, and thereby accidentally created two "Gregg Palmers" in the English-speaking acting profession. (DCOM: The Tenth Planet) Worse, since both of these faux-Palmers — for "Gregg Palmer" isn't the American's real name, either — were active in the 1960s, their credits can be easily confused.
He shared his memories of The Tenth Planet on the story's DVD audio commentary.