As mentioned before, Rodney Dangerfield. Didn't get his big break until he was 46. Made himself a legend.
Talk all the shit you want about Michael Bolton. That guy didn't have a hit until he was 34, and he's since sold 65 million records.
J.K. Rowling was 32 when she wrote Harry Potter.
Alan Rickman didn't star in a movie until he was 46.
Samuel L. Jackson was a social worker until he said "Fuck it, I'm gonna be an actor," and at age 45, he broke out with his role in Pulp Fiction.
Morgan Freeman's first big movie role came when he was 52.
Should I keep going? Or are you gonna get off your ass and pursue your God damn dreams?