Jay Scott Greenspan, better known by his stage name Jason Alexander, (born September 23, 1959) is an American actor, comedian and singer, best known for his role as George Costanza on the television series Seinfeld.
He appeared with Jerry Seinfeld in "When You Wish Upon a Weinstein" in an episode of Seinfeld as his character George Costanza. He also provided the voice of Louie Anderson in "There's Something About Paulie".
At The Drunken Clam in "The Movement", Peter and the guys watch an episode of Seinfeld edited down to about three seconds long thanks to syndication. Jason Alexander and the Soup Nazi are briefly seen.