There’s a pre-nosejob Peter O’Toole in Kidnapped.
Clint Eastwood as a lab tech in Revenge of the Creature (1955). Aww, he lost his rat, how cute 
I think he might be the most eventually-famous person to ever appear in a movie done on Mystery Science Theater 3000.
Bill Paxton is the only actor to be killed by a Terminator, a Predator, and an Alien.
Recently, the movie Mystic Pizza was on TV, and there was Matt Damon in his first movie role. He had one scene, and his only line was “Mom, do you want my green stuff?”
In a re-run of Married with children this week I was surprised to suddenly see Matt LeBlanc (pre-Friends) in a small part as Kelly’s friend Vinnie Verducci.
Here is the “King of Cool” in that 1958 movie he’d probably rather had been lost.
Though not really a minor role but his first main role.
Actually, that whole thing was about a MWC spin-off starring LeBlanc and Joseph Bologna as father and son Charlie and Vinnie Verducci. The spin-off series lasted a couple of months and there was occasional back and forth of characters between the two series.
People don’t like you, Mitchell. I don’t care for you much myself.
I’ve never seen either film, much less looked for her, but former First Lady Pat Nixon had bit parts in movies like “Becky Sharp” and “The Great Ziegfeld”
I think in Death Wish 2, there’s a young Lawrence Fishburne as one of the gang members too.
Oh yeah, another one I saw recently: Cuddy and (with hair) Taub are the “damn jews” who take Jack Nicholson’s favorite table in As Good as It Gets.
The “Rock Star” lipsynching to Guns’n’Roses at the start of the Dirty Harry film “The Dead Pool”. Oh he also appeared alongside Damon Wyans in “Earth Girls are Easy”.
I actually liked Wyans in that film. Shame.
Netflix Streaming is great for this. I picked an episode of 21 Jump Street at random yesterday, and it had David Paymer playing a pornographer of underage models. He was appropriately slimy.
Teri Garr was a regular cast member on the Sonny and Cher show. Steve Martin was a writer and also occasionally appeared on screen.
I remember seeing an old movie called “The Next Voice You Hear.” It starred a young actress named Nancy Davis, who would soon marry an actor named Ronald Reagan.
On this theme, I always have to laugh when I think of Patrick Swayze’s movie “Next of Kin.”
It has Liam Neeson as Swayze’s brother-a brainless hillbilly. The line which strikes me most goes something like Liam saying: “So, that’s why he done it! He wanted to get them his own self!” Priceless.
Also, Rob Reiner shows up in Gomer Pyle, USMC as a would be recruit when Gomer is working a recruitment booth.
Best wishes,
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Speaking of Rob Reiner jogged my memory. I’ve been watching Batman reruns on the Hub and have noticed Rob Reiner (in “The Penguin Declines”) and James Brolin (“Ring Around the Riddler,” “The Catwoman Goeth,” and “The Cat and the Fiddle”) appear in small roles.
I know, these aren’t films, as asked for in the OP, but Reiner has become a well-known film director and Brolin has had roles in both theatrical and TV films.
After Clint gets the rat out of his lab coat wondering how it got there:
Crow T. Robot: “This guy is bad, this is his first and last movie!”
Tom Servo: “Yeah!”