daddypa
Sir Weeble Wobblybottom
Sir William
Sir Winston Whines-A-lot
Sir Wyles of Ashencoat (a play on "Agincourt")
Sirana
Siren
Sirius
Sirus
Sisco
Siskel And Ebert
Sisko
Sissy
Sister
Sita
Sitar
Sitka
Sitsa
Sitting Bull
Siva
Siva (after the Hindu god of destruction)
Six
Six Toes
Sixer
Sixpence
Sixty-Niner
Sizi
Sizzle
Sjakie
Sjimmie
Sjors (Dutch version of George)