Peter Brocco, the Organian “Claymere” in “Errand of Mercy,” as crooked contractor “Theophile Duclerc” in Perry Mason’s “The Case of the Fraudulent Foto.” (1959)
Brent Spiner in “Independence Say” as the crazy director of that secret Area 51 facility.
“Independence Say” what? 
More from Perry Mason (the place where I’m currently residing shows episodes back-to-back from 06:00 to 12:00, followed by Columbo until 16:00):
Ken Lynch (Chief Engineer Vanderberg in “The Devil in the Dark”) in “The Case of the Stuttering Bishop,” and Jon Lorman (three “old man” roles in different episodes) as the doctor presenting evidence in the same episode.
WILD CARD: Perennially type-cast Vito Scotti as “D’Amato” in “The Case of the Howling Dog.” (You mention Columbo, you have to include Vito Scotti!)
Jon Lormer was Nathan Grantham in Creepshow (1982) but not Nathan’s shambling corpse. I should have recognized his voice.
Susan (Dr. Leah Brahms, ST:NG) Gibney — recurring role on Crossing Jordan.
Watched a old (94) TV movie called “Without Warning”. Score four Trek actors: Ron Canada (two roles), Alan Scarfe (two roles), Spencer Garret (Simon Tarses) and the biggie John Delancie (Q). Also a cameo of Arthur C. Clarke as himself. (It’s on YouTube for any SF buffs who haven’t seen this one.
A young George Takei (“Mr Sulu” himself) as “Toma Sakai” in Perry Mason’s “The Case of the Blushing Pearls” (1959).
John Anderson, “Kevin Uxbridge” in TNG’s “The Survivors,” as “Bud Ferrand” in Perry Mason’s “The Case of the Bartered Bikini” (1959).
William Campbell, “Trelane” and “Koloth,” as “Allen Sheridan” in Perry Mason’s “The Case of the Artful Dodger” (1959).
Jon “Old Man” Lormer (again) as the Medical Examiner in Perry Mason’s “The Case of the Lucky Legs” (1960).
Sally “Dr Elizabeth Dehner” Kellerman as “Grieving Widow Liz Houston” in Columbo’s “Ashes to Ashes” (1998).
Since Raymond Burr was gay, & Mr Takei is openly so, I wonder if any pearls were made to blush?
Leslie “Lt Palomas” Parrish as “Hope Sutherland” in Perry Mason’s “The Case of the Madcap Modiste” (1960).
Ken Lynch (again) as “Robert Hayden” in Perry Mason’s “The Case of the Irate Investor” (1960).
William Campbell (again) as “Jim Ferris” in Perry Mason’s “The Case of the Ill-Fated Faker” (1960).
The pearls were cultured. 
Whit “Mr Lurry” Bissel as slimebag “Max Pompey” in Perry Mason’s “The Case of the Lavender Lipstick” (1960.)
Jon Lormer (again) as the “Autopsy Surgeon” in Perry Mason’s “The Case of the Clumsy Clown” and “The Case of the Provocative Protege” (1960).
Kathie “Deela” Browne (the one space babe Kirk definitely banged) as “Donna Loring Ross” in Perry Mason’s “The Case of the Provocative Protege” (1960).
Skip “Melakon/Dr Sevrin” Homeier as “Dr Edley” in Perry Mason’s “The Case of the Pathetic Patient” (1961).
Liam “Parmen” Sullivan as “Tom Gilrain” in Perry Mason’s “The Case of the Crying Comedian” (1961).
Leslie “Lt Palomas” Parrish (again) as “Vivian Ames” in Perry Mason’s “The Case of the Impatient Partner” (1961).
Theodore “Korob” Marcuse as “Boyd Alison” in Perry Mason’s “The Case of the Jealous Journalist” (1961).
Jeanne “Mrs Crater” Bal as “Helen Rand” in Perry Mason’s “The Case of the Misguided Missle” (1961).
William “Nilz Baris” Schallert as “Dr Bradbury” in Perry Mason’s “The Case of the Misguided Missile” (1961).
Bill “McCoy Sr” Quinn as the “first judge” in Perry Mason’s “The Case of the Cowardly Lion” (1961).
Jason “Rael” Evers as “Stuart Benton” in Perry Mason’s “The Case of the Difficult Detour” (1961).
Paul “Dr Piper” Fix as “Prosecutor Hale” in Perry Mason’s “The Case of the Barefaced Witness” (1961).
Barry “Surak” Atwater as “George Albot” in in Perry Mason’s “The Case of the Waylaid Wolf” (1961).
Liam “Parmen” Sullivan (again) as “Lloyd Farrell” in Perry Mason’s “The Case of the Fickle Fortune” (1961).
John “Dr Boyce” Hoyt as “William Harper Caine” in Perry Mason’s “The Case of the Resolute Reformer” (1961).
Robert “Lazarus” Brown as “Frank Sykes” in Perry Mason’s “The Case of the Larcenous Lady” (1961).
Byron “Admirals Komak and Westervliet” Morrow as “the judge” in Perry Mason’s “The Case of the Larcenous Lady” (1960).
Wow. Did you actually watch all of those, or have you just been combing the Perry Mason cast listings?
I watched all of those, plus a number of others without Star Trek actors. The cable network where I’m staying shows them back-to-back from 06:00 to noon. I’ve dropped off a little this week because I was losing too much sleep.
As an aside, the last one I saw this morning had Kathie "Delia’’ Browne as the murderess and scrumptious Sherry “Andrea” Jackson as the innocent defendant. The actors already listed above have turned up as different characters in so many episodes that it’s getting tedious to keep track of them.