Nancy Jean Cartwright (born October 25, 1957)[1] is an American actress, voice actress and comedian, known for her long-running role as Bart…Nancy Jean Cartwright (born October 25, 1957)[1] is an American actress, voice actress and comedian, known for her long-running role as Bart Simpson on the animated television series The Simpsons. Cartwright also voices other characters for the show, including Nelson Muntz, Ralph Wiggum, Todd Flanders, Kearney and Database.