And a few that weren't so great. By Chip Carter at Moviefone.
SIR ALEC GUINNESS IN STAR WARS
An Academy and Tony Award winner and renowned star of stage and screen, Guinness shocked his peers when he took the role of Obi-Wan Kenobi in some weird little sci-fi film by an unknown director. But Guinness was shrewd enough to negotiate a piece of the action -- 2% of the take from 'Star Wars,' which made him filthy rich. He hated the character, and in fact, persuaded George Lucas to kill him off because he "just couldn't go on speaking those bloody awful, banal lines."
CHARLIZE THERON IN MONSTER
The beauty definitely turned into a beast here -- but she was amazingly good as the last female serial killer executed in the United States.
ROBIN WILLIAMS IN ONE HOUR PHOTO
You always knew under that comic exterior there existed an incredibly creepy little man. Here he is! Nanu nanu, suckers!
LEONARDO DICAPRIO IN TOTAL ECLIPSE
Leo was still a heartthrob and popping up on the cover of Tiger Beat in 1995 when he decided to change directions -- seriously change directions. He plays 16-year-old poet Arthur Rimbaud, gay lover of older, creepier poet Paul Verlaine, and even has an uncomfortably long full-frontal nudity scene. Teen girls everywhere were dismayed.
MARY TYLER MOORE IN ORDINARY PEOPLE
TV's version of Snow White played an ice-cold beeyotch. First-time director Robert Redford said his biggest challenge was making audiences believe it. It worked -- the film won four Oscars.
BRAD PITT IN FIGHT CLUB
When pretty-boy Pitt turned up in this 1999 classic as a raggedy, trash-talking brawler and human lard collector, our hearts melted.
GEORGE CLOONEY IN BATMAN AND ROBIN
"I'm Batman." No, you're not.
ROBERT DENIRO IN ANALYZE THIS
Bobby D? A comedian? Fuhgeddaboutit. All he'd ever been was mean and psychotic. Here, he was mean, psychotic -- and funny as hell.
RUE MCLANAHAN IN STARSHIP TROOPERS
The late Golden Girl was golden indeed as a blind biology professor in this sci-fi classic. Her cameo is made even more memorable by the fact that Denise Richards pukes in the scene.
BILL MURRAY IN THE RAZOR'S EDGE
Sure, there have been plenty of movies where Bill Murray wasn't funny -- but this was the first one where he wasn't supposed to be funny. This 1984 remake of the W. Somerset Maugham classic was a box office bust with Murray in the same role that Tyrone Power played in the 1946 film that was nominated for four Oscars. The reception was so harsh, Murray took a four-year break from show biz.
HERMAN MUNSTER IN MY COUSIN VINNY
Fred Gwynne shed his big ol' boots for a judge's robe in one of the most "What?!?" moments in movie history. What is a "yoot," anyway?
JULIE ANDREWS IN S.O.B.
Mary Poppins shows her breasts. 'Nuf said.
THE ENTIRE CAST OF AIRPLANE
At the time the Zucker Bros. were filming this classic collection of one-liners and inanities in 1980, casting stoic Hollywood heroes Leslie Nielsen, Lloyd Bridges, Robert Stack and Peter Graves in parodies of their stolid film personas seemed like the worst idea ever.
JOHNNY DEPP IN CRY-BABY
He got his start in the first 'Nightmare on Elm Street' and became a teen idol on '21 Jump Street.' People thought he'd flipped his wig when he turned up in John Waters' 1990 parody of teen musicals. Just in case the little girlies thought he was kidding, Depp also starred in 'Edward Scissorhands' that same year. After that, it was just the little emo girls who wanted to take him home.
(Full article at Moviefone.com)