Warren “Rojan” Stevens in Perry Mason’s “The Case of the Empty Tin.”
John Hoyt as a US Treasury agent in 1949’s Trapped.
Philip Pine, ‘Col. Green’, from ‘Spectre of the Gun’ in ‘The Set-up’ (1949). Not sure I would have recognized him if I hadn’t already seen his name in the credits, but still had those same menacing eyebrows. Also Hal Baylor, who played a cop in ‘City on the Edge of Forever’, played a boxer.
I did a search for him on another matter and was surprised to find he was also in “I, Mudd” and the TNG movie First Contact. I’ve never spotted him in either.
Nitpick: The episode was “The Savage Curtain.”
Michael “Apollo” Forest as a punk in The Twilight Zone’s “Black Leather Jackets.”
Just caught Barbara “Philana” Babcock in an episode of Murder, She Wrote,
I saw Yeoman Rand in an ep of The Real McCoys–and for once she wasn’t playing a stripper. She was a cologne salesperson trying to use her sex appeal to get Richard Crenna to purchase.
Laurence “Sybok” Luckinbill as the victim in Columbo’s “Make Me a Perfect Murder.”
John “Mr Hengist” Fiedler as a knife-murderer in Alfred Hitchcock Presents’ “Incident in a Small Jail.”
Antoinette Bower as “Nurse Greco” in Alfred Hitchcock Presents’ “A Woman’s Help.”
Robert Picardo, the holographic doc from Voyager, spotted as Sheldon’s snooty Heidelberg professor in Young Sheldon: “A Roulette Wheel And A Piano Playing Dog”.
Off-topic: after seeing Picardo play Meg Mucklebones in Ridley Scott’s Legend, I believe that actor can do anything.
Piglet committed murder twice? I’m so disappointed. 
Yup. He seems to have a problem dealing with women. 
Michael Ansara in Alfred Hitchcock Presents’ “The Babysitter” and “The Orderly World of Mr. Appleby.”
John Harmon, the bum who gets zapped by McCoy’s phaser in “The City on the Edge of Forever,” as the murder victim in Alfred Hitchcock Presents’ “Help Wanted.”
Warren Stevens as the murder victim in Alfred Hitchcock Presents’ “Never Again.”
Malachi Throne as "Sandifer’ in Perry Mason’s “The Case of the Simple Simon,”
William Schallert as a traveling salesman in an episode of The Waltons.
Frank Gorshin in a walk-on role in Alfred Hitchcock Presents’ “Decoy.”
Skip Homier as an accidental murderer in Alfred Hitchcock Presents’ “Momentum.”
Paul Fix in The Twilight Zone’s “I Am the Night—Color Me Black.”
Nehemiah Persoff in yellowface in The Wild, Wild West’s “The Night of the Deadly Blossom.”