I’m guessing this, but technically he’s in several different scenes.
Wallet Guy is acting up a storm
With no lines and little more than the back of his head appearing on camera, Glen Coco…
Well, I assumed that whatever parameters I set there would we dopers who would flex them. 
Was Bronson Pinchot in only one scene in Beverly Hills Cop? Regardless, he was a highlight of the film and at the very start of his career.
Another Back to the Future II example-- the angry baseball bat-wielding Black father who went after Marty and ended up tearing up his daughter’s room when he thought Marty had come to harm her.
“Look, I just made a mistake!”
“YOU DAMN RIGHT YOU MADE A MISTAKE!”
That would be his second entry on the list. He appeared upthread as “Second Jive Dude” (he’s on the left) in Airplane!.
That’s how I remember it, I could check, but…well, I’m very busy today.
That’s Gene Hackman.
Richard Harris as the RAF pilot at the beginning of The Guns of Navarone
How much of that was because he just looked COOL? I don’t remember thinking the character was all that cool, but damned if he didn’t look super cool anyway.
He’s in 2 scenes. The first one from the OP and the 2nd when Axel brings Billy to the gallery because he wants Jenny to open up the warehouse for them. Billy asks if it’s a bother to get him an espresso with a lemon twist and Serge says, “No, don’t be stupid.” Maybe that’s the genesis of his “Don’t be ridiculous” catchphrase on Perfect Strangers.
I remembered another scene stealing moment from Annie Hall: Marshall McLuhan.
Of course, McLuhan is not a professional actor (as shown by the fact that he flubs his line: “You mean my whole fallacy is wrong.”), but I don’t think that should disqualify this example. He still completely steals the scene, and his mistake barely registers the first time you see it, because his appearance is so unexpected.
I just realized that that’s one uninterrupted shot of almost three minutes, with intertwining dialog handled perfectly by the main actors. Little wonder Woody didn’t want to do another take.
And in ROTJ, we learn he can fly?!? When I grow up, I want to be a freelance bounty hunter with awesome armor and a jetpack and a cool ship that looks like a snail.
I think Boba Fett’s extreme popularity was less because of his look than because his action figure was available to fans as a mail-away item well before he appeared on screen. He was cool because only the “cool crowd” knew him before he appeared in film.
Excellent example. And a fine bit of silent acting between the African-American actress (whose name is unfortunately lost) and Geena Davis; the unknown woman’s little nod says, “You see what I can do?” And Davis’ look says, “Okay, I’m impressed.”
Before making this post, I Googled to try to find the actress’ name. Unfortunately, since she had no lines, she was never credited. But I came across an interesting article by a journalist who tried to find her. It points out that the producers included that scene for just exactly the reason you said - to acknowledge the existence and exclusion of black female athletes while remaining historically accurate.
That’s not the scene that gets my tear ducts working, though; instead, it’s the scene when Ann Cusack’s Shirley Baker is trying to find her name on the roster, and Anne Ramsay’s Helen discovers, without shaming her, that Shirley can’t read, then shows her that she’s on the team. I can’t imagine a realistic scene of a male athlete of the time showing such sensitivity or compassion. Although the male coach has a very sweet smile at the end of the scene, when he tells Shirley “go join your team.”
Well, not just that – he had appeared in the despised Star Wars Holiday Special in an animated short – arguably the best and coolest part of that entire production (and which suggested, at first, that he was a “Good Guy”)
The “a what?” guy from Jaws:
Astronaut Jim Lovell appeared in the final scene of Apollo 13 greeting Tom Hanks’ character on the aircraft carrier, upon Apollo 13’s safe return.