Robert Downey Jr.

The son of an underground filmmaker, Robert Downey Jr. was born April 4, 1965, in New York City. His first big-screen part was as a puppy in his father's film Pound (1970).

After a series of memorable supporting roles -- including one in Weird Science (1985) -- Downey joined the "Saturday Night Live" cast for one season. He soon moved to Hollywood and landed the lead in The Pick-Up Artist (1987). His turn as a drug addict that same year in Less Than Zero eerily foreshadowed the personal demons that would haunt him later.

Downey moves with ease from comedy (Soapdish) to drama (Short Cuts) to the bizarre (Natural Born Killers). He earned a Best Actor Oscar nomination for his note-perfect portrayal of the title character in 1992's Chaplin and a second Oscar nod 16 years later for Tropic Thunder. 2009 brought him a Golden Globe win as Best Actor for his performance in Sherlock Holmes.