Dominic Keating (“Malcolm Reed” in ENT) as “Murray Stone” in the Inspector Morse episode “Dead on Time.”
Jeffrey Hunter, Captain Pike from TOS “The Cage”, played a military engineer, John Hunter in “The Longest Day”. He is heroically killed while blowing up German stuff on D-Day.
Bill Cobbs, a hard-working character actor who’s been in everything (and whom I once met in Cleveland, his hometown), plays a bartender in one of my favorite comedies, Trading Places, which I saw again last night:
John Fiedler, Heingist from the TOS episode, “Wolf in the Fold” played a reluctant bank theif on Have Gun Will Travel, “The Gold Bar”.
Jane “Amanda” Wyatt in the 1948 noir Pitfall.
Sherry “Andrea” Jackson as “Terry Williams” in The Danny Thomas Show episode “Boarding School” (SE 4, EP 1, 1956). She was smokin’ hot even at 14! 
Another Friends spotting: Dina Meyer, later to portray a Romulan officer in one of the movies (she was in Starship Troopers, too), as an aspiring young actress cast with Joey in a new play.
Ken “Chief Engineer Vanderberg” Lynch as State Trooper “Captain Barker” in The Andy Griffith Show episode “The Manhunt” (SE1 EP 2).
Just rewatched one of my favorite B-movies, The Hidden, about an alien criminal on the run in Eighties LA, and spotted four ST alums:
Vic Perrin played Tharn in “Mirror, Mirror”. He was in the Have Gun Will Travel episode, “Everyman”. An interesting episode based on a tarot reading.
Elinor Donahue (“Commissioner Hedford” in “Metamorphosis”) as Sheriff Taylor’s girlfriend “Ellie Walker” in early episodes of The Andy Griffith Show. She’s still around at age 84.
While looking at the cast of the show and its immediate successor, I found that Sheldon Collins was in two episodes of Mayberry RFD in 1968. Trek fans know him as the tough kid with the switchblade in “A Piece of the Action.” He also played young Tony Newman in the Pearl Harbor episode of The Time Tunnel.
Not an actor, but the town of Mayberry was standing in for New York in, “The City on the Edge of Forever.” (Sorry if this was mentioned earlier.)
(Did it really take this long to mention Ms Donahue? I’m embarrassed for all of us.)
Floyd’s Barber Shop in particular.
Is ANYONE in New York named Floyd? 
Only if they’re visiting from rural North Carolina.
That Hawaii Five-O episode with Joanne Linville has been on my mind lately with all of the news about Elizabeth Holmes and Theranos. In that episode, her character claimed to have a machine that could diagnose any disease with one drop of blood. In the dramatic courtroom climax, she demonstrates her machine by testing McGarrett, and announces that he has—gasp—cancer! Then it’s revealed that McGarrett swapped his blood sample with a drop of food coloring.
BTW, Joanne Linville died on June 20 of this year. Most of the obituaries I saw mentioned her Star Trek role first—sometimes in the headline:
Check this pic of Linville and her daughter.
I saw a picture of them. Very cool
Love it!
Spock’s love child would have made a great story. Too late now… 