There is a difference between a film actor and a movie star. Though a film actor can fill a role, perhaps even garner praise and awards, a movie star generates heat, excitement and, ultimately, dollars for a film. An actor is in a movie. A movie star is the movie.

But movies stars are not born. They are not made, either, despite what some studio heads proclaim.

No, a star comes into existence when an actor lucks into the right part in the right film at the right time. A star is made in a single breakout role. Here are five examples of movie stars who were elevated by finding such a part.

TOM CRUISE: Before Risky Business (1983), he was just another attractive teen actor with a killer smile. All that changed when he slid across floors in his drawers and found his aw shucks persona and an unparalleled opportunity, playing a naive, privileged son thrust into the world of high-dollar prostitution. Perhaps any actor would have excelled in this surprisingly sophisticated comedy, but it's the still stellar Mr. Cruise who got the part.

GRETA GARBO: She had been in successful silent films, both in America and her native Sweden, but it was her first talkie, Anna Christie (1930), that showed her to be an actress of surprising depth. Her strong performance as a prodigal daughter whose relationship with her father becomes strained because of a life lived on society's fringes earned Garbo her first Oscar nomination and made her a star.

AL PACINO: A skilled stage actor who had proved his talent in a few films, most notably Panic in Needle Park , Mr. Pacino announced himself as a star as conflicted son Michael Corleone in The Godfather (1972). So powerful was his performance that he overpowered the other dramatic bright lights -- Robert Duvall, James Caan and the inimitable Marlon Brando.

PETER O'TOOLE: Mr. O'Toole had done a few films and some television before 1962, but they were all but lost in the long shadow cast by Lawrence of Arabia . His outsize T.E. Lawrence was just the sort of character needed to match the vast scale of the movie and to make a young and exciting actor a legend.

MERYL STREEP: Only Julia predates The Deer Hunter (1978) on Ms. Streep's film rÃsumÃ. Although her first film set her up as an actress with rare gifts, it was playing the young wife left behind in The Deer Hunter that cemented her reputation as one of cinema's great performers. In the 30 years since, Ms. Streep has been nominated for 14 Academy Awards and has won two. That's star power.