Nimoy appeared in many films and TV series, some of them long before Star Trek. I was watching videos of Perry Mason and I saw him in one. YouTube doesn't seem to have the full episode, but they have the final scene:
I watch a lot of old westerns. I often see Leonard Nimoy and DeForest Kelley (Bones) playng parts in them. I also often see Gene Roddenberry's name as a writer in the credits.