Just spotted Bill Erwin again, playing a WWII vet visiting the White House on The West Wing.
Christopher Lloyd was also on The West Wing in a different episode, playing a jovial legal scholar helping a delegation from Belarus write a new constitution for their country.
Watched “Thirteen Days” last night. This dramatization of the events of the Cuban Missile Crisis featured no fewer than seven Trek actors. The Kennedy brothers, Jack and Bobby, were played by Bruce (Capt. Pike) Greenwood and Stephen (Major Hayes) Culp.
Bill Smitrovitch, who was in the DS9 two-parter “Past Tense” played Maxwell Taylor and Ed Lauter, who portrayed the father of a dead cadet in “The First Duty” played some random military figure. Len Cariou, who played Captain Janeway’s late fater, played cold warrior Dean Atchison.
In real life, part of what led to the resolution of the crisis was a “back channel” involving a newsman and a KGB officer. Both were played by Trek actors Jack Blessing (Agent Dulmer) and Boris Krutonog, who, per IMDB, had some role in “Undiscovered Country”, but I really don’t remember the character.
Looks like Krutonog played one of Sulu’s Excelsior Bridge crew.
Shirley Bonne (“Ruth” in “Shore Leave”) and luscious Teri Garr (“Roberta Lincoln” in “Assignment: Earth”) as “Sharon” and “Estelle” in That Girl’s “This Little Piggy Had a Ball.”
Also on The West Wing: Terry O’Quinn as an Army general and Chairman of the Joint Chiefs of Staff…
…and Ron Canada as a senior State Department official.
William Schallert, Nilz Barris in the Trouble With Tribbles, in the Rawhide episode Incident With the Executioner, as “The Salesman”. He runs off in Indian territory, and we do not learn what happens to him. Perhaps he takes up teaching High School.
Andrea Martin as a nib-nosing aunt or cousin in My Big Fat Greek Wedding.
Just saw Jason Alexander as a suicidal office worker on Friends.
And Robert Picardo as a Federal judge on The West Wing.
And Mitchell Ryan as a U.S. senator on the same episode of The West Wing.
John Anderson (again!) as rainmaker “Tulsa Weems” in the Bonanza episode “Rain from Heaven.”
William Schallert, Nilz Baris in The Trouble With Tribbles, as Dallas Burchfield in the Have Gun Will Travel episode, Justice In Hell.
Stanley Adams, also from The Trouble With Tribbles, in the Wagon Train episode, The Trace McCloud story.
Morgan Woodward (again!) and Kathie “Deela” Brown in Bonanza’s “The Toy Soldier” and “The Waiting Game,” respectively.
James “Scotty” Doohan and Philip “Col Green” Pine in the Bonanza episode “The Legacy.”
I’ve recently seen Seymour Cassel as a friendly barber in Rushmore
And Steven Culp as the conservative Speaker of the House on The West Wing
James Cromwell as a former President on The West Wing
Lee Delano as a sardonic NYPD sergeant in Ron Howard’s Splash
And Clint Howard, Ron’s brother, as a wedding guest, also in Splash
Teri Garr (again!) as an actress at an audition in That Girl’s “The Drunkard.” Sid Melton (“Alf Monroe” in Green Acres) and Sid Caesar are in this episode too.
Honestly, if you were a casting director, which one would you choose? 
Ron Soble, Wyatt Earp in TOS Spectre of the Gun in Rawhide Incident West of Lano, as a bad guy named Morrow.
Another bad guy sounds and looks like Ken Lynch from The Devil In the Dark, but he isn’t listed.
I just finished watching, “The Greatest Story Ever Told,” for the first time and I can’t believe how many Trek actors are in it: Mark Lenard, Michael Ansara, Abraham Sofaer, Celia Lovsky, John Abbott – there may be one or two more.
Jeffrey Hunter, Captain Christopher Pike, played Jesus in King of Kings.
I’m sorry, are we just doing TV shows?
I’ll sneak this one in, just in case:
The Rifftrax guys tackled, “Kingdom of the Spiders,” with Shatner. They’re good, KotS isn’t.
It was expanded to films some time ago. Thanks!