Although it isn't a written rule, an "extra"—a background player in a movie or TV show—usually has no spoken lines. If a line, or a few lines, are spoken, the person is often referred to as a "bit player" instead of an extra. (If a major star or a "known" actor is an extra in a movie, their non-speaking appearance is called a "cameo.")
The famous people listed below all made one or more appearances as movie extras before they went on to bigger and better things.
1. Sylvester Stallone
Sylvester Stallone was an extra in Woody Allen's 1971 film Bananas as a subway mugger. He was also an extra in Jane Fonda's 1971 psychological thriller, Klute, as a disco patron (uncredited).
2. Brad Pitt
In 1987's Less Than Zero, Brad Pitt was an extra billed as "Partygoer / Preppie Guy at Fight."
3. Clint Eastwood
In the 1950s, Clint Eastwood was actually an eager member of Central Casting. He was an uncredited extra in several films before breaking into leading man roles.
4. Phil Collins
At the young age of 13, Phil Collins was an extra in the audience, cheering and screaming for the Beatles, in their first film, A Hard Day's Night, in 1964. (Phil wasn't shown in the actual film.)
5. Patti Boyd
Another interesting extra in A Hard Day's Night was model Patti Boyd, who met George Harrison while filming the movie, became his girlfriend, and married him two years later, in 1966.
6. Rudolph Valentino
Rudolph Valentino was an extra in several silent films before he became a leading man and heartthrob known as the "Latin Lover."
7. Noël Coward
At age 19, Noël Coward was an extra in Hearts of the World, a 1918 D.W. Griffith silent film.
8. Ayn Rand
A 22-year-old Ayn Rand was an extra in Cecil B. DeMille's 1927 silent film, The King of Kings.
9. Renée Zellweger
Renée Zellweger was an extra, playing one of the girls in 1993's Dazed and Confused.
10. John Wayne
In the 1920s, John Wayne was an extra in several silent films before his first starring role in 1930's The Big Trail.
11. Clark Gable
Clark Gable was also an extra in several 1920s silents, including Erich von Stroheim's The Merry Widow.
12. Megan Fox
Megan Fox was an extra in Bad Boys 2 (2003) as a dancer in a club scene.
13. James Dean
In the Dean Martin and Jerry Lewis comedy Sailor Beware (1951), James Dean was an extra with one line: "The guy's a professional."
14. Ben Affleck & 15. Matt Damon
Ben Affleck and Matt Damon (not pictured) were extras for the Fenway Park scenes in Field of Dreams (1989).
16. Jackie Chan
As a teenager, Jackie Chan was an extra in two Bruce Lee films: Fists of Fury (1971) and Enter the Dragon (1973).
17. Jean Harlow
Jean Harlow (and her mother) was an extra in several silent films in the late 1920s, when she was in her late teens.
18. Bruce Willis
Look carefully and you'll spot Bruce Willis as an extra in the courtroom scene of Paul Newman's 1981 film, The Verdict.
19. Marilyn Monroe
Marilyn Monroe is often referred to as an extra in her first-ever screen appearance, 1948's Scudda Hoo! Scudda Hay! Marilyn has one line ("Hi Rad") and can also be briefly glimpsed sitting in a canoe with another actress.