Jerry Seinfeld Jerry Seinfeld Actor Julia Louis-Dreyfus Elaine Benes Actor Jason Alexander George Costanza Actor Michael Richards Cosmo Kramer Actor Wayne Knight Newman Guest Star Estelle Harris Estelle Constanza Guest Star Jerry Stiller Frank Costanza Guest Star Liz Sheridan Helen Guest Star Barney Martin Morty Guest Star Len Lesser Uncle Leo Guest Star John O'Hurley J. Peterman Guest Star Jay Leno Himself Guest Star Ron West Dr. Strugatz Guest Star Tim DeZarn Salesman Guest Star Michelle Bonilla Waitress Guest Star Larry David Executive Producer George Shapiro Executive Producer Howard West Executive Producer