Swizzle Stix
Swoozie
Sy
Sybil
Sycko
Sydney
Sydni
Syiah
Syian
Sylmony
Sylvester
Sylvester Francis
Sylvia
Sylvie
Sylvin
Syma
Symba
Symeon
Symon
Sympathy
Symphony
Synda
Syndey Renee
Syndi
Syndrome (after the character in the movie "The Incredibles")
Synergy
Syntax
Syracuse