Yes, the Old Ones.
Whit Bissel (“Mr Lurry”) as crewman “Yo Yo” in the war flick Destination Tokyo (WB, 1943).
Anthony Caruso (“Bela Oxmyx”) as paratrooper “Miggleori” in the war flick Objective: Burma! (WB, 1945).
Other memorable cast members include John Forsythe (Bachelor Father, Dynasty) as “Sparks” and Hugh Beaumont (Leave It to Beaver) as “Capt. Hennessey,” respectively.
Have I mentioned Rene Auberjonois, Odo of Deep Sppane Nine, as Alar in Stargate SG–1? Watching it now.
Do I win a cookie or something when the thread hits 2000?
The old TV show “The Fugitive” aired at roughly the same time as ST: TOS so naturally you’d expect a fair amount of cast overlap, but one episode in particular merits notice in this thread. In “Home is the Hunted”, Richard Kimble returns to his home town for the first time since his false conviction. We meet his family, his brother was portrayed by Andrew Prine, who later would be in the miniseries “V”, as well as the TNG episode “Frame of Mind”. His brother-in-law was played (this time, at least) by James Sikking, who would later become known for his portrayal of Lt. Howard Hunter on “Hill Street Blues”. But to ST fans he will always be known for playing Captain Styles of the Excelsior in “The Search for Spock”. One of Kimble’s nephews was played by Billy Mumy, who went from “The Twilight Zone” to being “Lost in Space” to “Babylon 5”. He did one Trek appearance in “The Siege of AR-558”. The other nephew was played by Clint Howard, who appeared as Balok in the TOS episode “Corbomite Maneuver” and also did episodes of DS:9, Enterprise, and Discovery.
Quite the family.
Saw a little bit last night of a 1976 Columbo episode with William Shatner as the bad guy and Walter Koenig as an LAPD detective.
Cool.
By golly, you’re right. Hasn’t changed a bit.
Charles “Commodore Stocker” Drake as “Sheriff Matt Warren” in It Came from Outer Space (1951). Other memorable actors in this gem are Russell “The Professor” Johnson and perennial “Oh, that guy!” Dave Willock, last seen here in Queen of Outer Space.
Saw a 1963 episode of Dr. Kildare the other night with Leonard Nimoy. Significant character but not enough to be listed in the opening credits.
He played the special friend of a blind woman. He liked to read a lot so they gave him thick glasses. Nimoy seemed to work out excuses to take the glasses off so he could, you know, see what was going on.
This episode also had Forrest Tucker in at as the POTW. (Fellow F Troop star Ken Barry appeared in 25 episodes of Kildare. James “The bugler” Hampton appeared on one episode. A couple lesser folk from the show also appeared.)
Good point.
Glenn Corbett (the original “Zephrem Cochrane”) as a police sergeant in 1969’s How to Commit Marriage with Bob Hope, Jackie Gleason, et al.
A friend reminded me that Adam Scott, of Parks and Rec and now the very unsettling but excellent sf workplace drama Severance, also has a ST movie credit.
Miko Mayama (Yeoman Tamula in “A Taste of Armageddon”) played “Fumiko” in The Hawaiians (1970). As Chuck Heston strips to share a communal bath with Japanese laborers on his pineapple plantation, he asks if any of the others in the bath “speakee pidgin.” At that moment, Fumiko steps up to the bath, drops the towel she’s been holding over her lower half, gets in and announces “My name is Fumiko. I speak.” Chuck ogles her voluptuous figure and asserts: “Fumiko, you don’t need to speak.” It was arguably the best scene in the flick.
As was noted elsewhere, “In Japan, men come first.” 
Armin Shimerman had a significant recuring role as Principal Snyder on Buffy the Vampire Slayer
Recently saw the very funny 1979 comedy The In-Laws with Peter Falk and Alan Arkin. A little poking around revealed that there were no fewer than six future ST alums in the cast:
David Paymer, in his screen debut, plays a scruffy cabbie: David Paymer | Memory Alpha | Fandom
John Hancock plays a U.S. Treasury official: John Hancock | Memory Alpha | Fandom
John Hostetter plays a handyman: John Hostetter | Memory Alpha | Fandom
Ed Begley Jr. plays a young CIA agent: Ed Begley, Jr. | Memory Alpha | Fandom
Rosana DeSoto plays a dental assistant: Rosana DeSoto | Memory Alpha | Fandom
And Richard Libertini plays an eccentric banana-republic dictator: Richard Libertini | Memory Alpha | Fandom
Just saw John Billingsley as an accountant in a 2011 episode of Suits: John Billingsley | Memory Alpha | Fandom
Also recently seen:
Ben Vereen as a singer/dancer in All That Jazz.
Wallace Shawn appears in the same movie as a Broadway suit.
James Cromwell plays a pioneering roboticist in I, Robot.
While Bruce Greenwood appears as a robot-manufacturing company’s CEO.
George Coe appeared in The Dove, a 1968 Oscar-nominated short parody of Bergman films (thanks to Burpo for the link: https://www.youtube.com/watch?v=L1TlAd6M-xU&ab_channel=artrory/).
That’s some set of peepers you got there, E_s_H. Thanks for the shout-out.
I’ve been binging, The Wild Wild West. You wouldn’t believe the Star Trek actors on there. And sets. I might just make a list. Stay tuned.