San Francisco garter snake 
Scarlet kingsnake 
Scarlet snake 
Schokar's Bronzeback 
Slender Snail Sucker 
Small-banded Kukri Snake 
Smooth Snake 
Smooth-scaled Mountain Rat Snake 
Sonoran Whipsnake 
Southeastern Crown Snake 
Southern black racer 
Southern Bronzeback 
Southern ring-necked snake 
Southern Smooth Snake 
Speckle-headed whipsnake 
Specklebelly Keelback 
Speckled Kingsnake 
Speckled racer 
Spotted bush snake 
Spotted dagger-tooth tree snake 
Spotted Ground Snake 
Spotted Keelback 
Spotted Leaf-nosed Snake 
Sri Lanka Blossom Krait