James Gregory (Inspector Luger) was Senator Iselin in The Manchurian Candidate, the Gorilla General in Planet of the Apes, the creepy sanitarium doctor in that one episode*
Jack Soo was a lot of people. A character actor with a long string of credits, you're most likely to remember him in various roles on M*A*S*H. He also played Sammy Fong in Flower Drum Song.
And, of course, Abe Vigoda's best-known role before this was as Sal Tessio in The Godfather.
