Fans paying attention may notice an overlong pause between William Shatner and DeForest Kelley’s names in the opening credits for Star Trek III: The Search For Spock. This is intentional — that’s normally the period in which Leonard Nimoy’s name would appear. 

Nimoy’s participation in the movie as an actor was kept as secret as possible during shooting, with a character named “Nacluv” played by “Frank Force” on call sheets distributed during production. Nimoy also used the pseudonym in the end credits for his cameo as the turbolift voice on the Excelsior.