Ruthie Cohen, the cashier in the coffee shop.
WikiSeinRuthie Cohen is a cashier at Monk's Cafe. She has the fifth-most appearances of any character on Seinfeld, behind only Jerry, Kramer, Elaine, and George. She was the cashier in almost all of the episodes and features most prominently in “The Doll”, with most of her speaking lines coming in...
https://seinfeld.fandom.com/wiki/Ruthie_Cohen