Today's celebrity birthdays: Sat., May 21Singer Ron Isley of the Isley Brothers, 75Guitarist Hilton Valentine of the Animals, 73Actor Richard Hatch ("Battlestar Galactica"), 71Keyboardist Bill Champlin (Chicago), 69Singer Leo Sayer, 68Actor Mr. T, 64Drummer Stan Lynch (Tom Petty and the Heartbreakers), 61Actor-director Nick Cassavetes ("The Notebook"), 57Actress Lisa Edelstein, 50Actress Fairuza Balk ("The Waterboy"), 42Singer-guitarist Mikel Jollet of Airborne Toxic Event, 42Rapper Havoc of Mobb Deep, 42Actor David Ajala ("Black Box"), 30Actress Ashlie Brillault ("Lizzie McGuire"), 29Actress Sarah Ramos ("Parenthood," "American Dreams"), 25