Star Trek III: The Search for Spock (1984)
Star Trek III: The Search for Spock is the Star Trek film that exists primarily to undo the consequences of the previous Star Trek film. Christopher Lloyd plays the Klingon commander Kruge.
Walter Koenig joined Star Trek in its second season, playing Chekov, a character reportedly added to appeal to younger viewers, with an accent Koenig constructed himself.
He wrote several scripts across the franchise’s animated series and continued in the role across the films.
Babylon 5 gave him Bester, a telepathic secret policeman of genuine menace, which is entirely at odds with Chekov and is the better performance. His son died by suicide in 2010 and he has campaigned on mental health since.