And Whoopi Goldberg who until then had only been a comedian.
I second the cast of THE REPLACEMENTS, Henry Rollins, Ice-T and David Bowie.
Laugh if you will but I like Mila Jovavich in the RESIDENT EVIL movies.
Which he originated on Twin Peaks. And to this day, Mr. Rilch and I can’t hear the term MO without bleating “Modus operandi!”
Juliette Lewis has an Oscar? Ew. For what?
Well yeah … a Tony award winning song and dance man who originated the role of El Gallo in The Fantastiks and Billy Flynn in Chicago. He also appeared in the original casts of Promises, Promises and Forty Second St. Oh and he did Threepenny too. And Carnival. And Annie Get Your Gun
He had a hell of a career for a non-actor. 
She was nominated (Best Supporting Actress) for her role in Cape Fear, but she didn’t win.
You’re only saying that because he won TWO Oscars for that role (only person to ever do so)
I vote for Max Pirkis, who had significant parts in both Master and Commander and the HBO miniseries Rome. He had never done a thing before M&C, and chooses to live a normal life instead of acting. That kid is an absolute natural and I wish he would take more parts. His character in M&C had me in tears in the beginning, middle and end of that film.
I came here to mention Bruno S. He is amazing in Kaspar Hauser and in Stroszek as well. Herzog wrote Stroszek for Bruno because he had cast Klaus Kinski as the lead in Woyzcek in stead of him. (And that was not a bad decision by Herzog, as we now have 2 great -cek/-zek films in stead of one.)
There’s a whole genre of “Stand up comedians who go on to star in successful sitcoms named after them”: Jerry Seinfeld, Roseanne Barr, Ray Romano, Bernie Mac
I would have to disagree. Whoopi Goldberg was never a stand up comedian. She was a stage actress who played multiple characters in a one woman show. She was never a “Did you ever notice” kind of comedian. She has always been an actor but moved from stage to screen.
And don’t forget about Mos Def in the rappers.
He was really good in Something the Lord Made.
Gilbert R. Hill played Inspector Todd, the long-suffering and rant-delivering boss of Eddie Murphy’s Detective Axel Foley character in the Beverly Hills cop movies. Hill was suited for the role, which was his first: he was a Detroit cop. He later went on to serve as a city councilman, and lost a bid for mayor.
He was perfect as Ford Prefect! I thought the guy who played Ford in the BBC production was way off, but Def had the appropriate BT,DT attitude. Plus, he was physically right. Tall, skinny, bald, tan and homely. A British Hunter Thompson.
Chief Dan George was 60 before he got an acting job- before then he’d been a construction worker and jack of all trades. After his first acting job he only acted in two more roles (supporting roles in forgotten western TV shows) before being cast in his first major role in a big-budget picture- Lodgeskins/Grandfather in Little Big Man. He hit a home run, was deservedly nominated for an Oscar (it went to John Mills for Ryan’s Daughter) and worked for as much as he wanted to for the rest of his life. More importantly to him perhaps was that he probably did more in that movie to make people reconsider Hollywood treatment of Indians than any actor before or since; seeing it as a kid was when I stopped thinking of Custer as a hero.
He also had the opportunity to say (and nail) some great lines:
*It was an excellent copulation.
I mounted a white woman once. She did not seem grateful at all.
Sometimes the magic works. Sometimes it does not.*
Referring to his new Snake Clan wife: *She cooks dog very well. She also has very soft skin. The only trouble with snake women is they copulate with horses, which makes them strange to me. She say’s she doesn’t. That’s why I call her “Doesn’t Like Horses”. But, of course, she’s lying. *
And of course, the speech when he’s blind and holding a scalp he once took- ferklempt first time I saw that.
*Do you see this fine thing? Do you admire the humanity of it? Because the human beings, my son, they believe everything is alive. Not only man and animals. But also water, earth, stone. And also the things from them… like that hair. The man from whom this hair came, he’s bald on the other side, because I now own his scalp! That is the way things are. But the white man, they believe EVERYTHING is dead. Stone, earth, animals. And people! Even their own people! If things keep trying to live, white man will rub them out. That is the difference. *
And his death prayer to the Cheyenne (Tsitsitas/Human Being) gods:
*Come out and fight! It is a good day to die! Thank You for making me a Human Being! Thank You for helpin’ me to become a warrior! Thank You for my victories, and for my defeats! Thank You for my vision, and the blindness in which I saw further! You make all things and direct them in their ways, O Grandfather. And now You have decided the Human Beings will soon walk a road that leads nowhere. I am gonna die now, unless death wants to fight. And I ask You for the last time to grant me my old power to make things happen. Take care of my son here. See that he doesn’t go crazy. *
He was amazing in all of his movies (Poetic Justice comes to mind), and, I might add, more than just a handsome face. His death was a pity…his acting skills were so natural that an Oscar at some point would not have been out of the question.
Dennis Rodman did a great appearance on Third Rock From The Sun as a space alien friend of the Solomons. Of course, he looks the part and does have atheletic abilities that could be considered alien.
It may not qualify exactly, but I liked the scene in Star Trek IV where Chekov is looking for the base: “Excuse me I’m looking for the nuclear wessels”.
Apparently they just filmed unknowing passers-by and used the best footage. There’s also a real motorcycle cop who stares at Chekov. 