It's the nickname for "Seinfeld" character Yev Kasem, a role based on a real NYC cook
The Soup Nazi is also the nickname of the eponymous 
character, Yev Kassem, ... Thomas, who did not realize that the character was 
based on a real person,... [DOC] [TLE] List of Seinfeld minor characters - Wikipedia [PAR] The television show Seinfeld featured many minor characters.