Six-lined racerunner 
Slender Rainbow-Skink 
Slender Snail Sucker 
Slow worm 
Small Broad-tailed Smooth-scaled Gecko 
Small Pacific Iguana 
Small-banded Kukri Snake 
Small-eyed Snake 
Small-spotted lizard 
Smith's Mountain Pit Viper 
Smiths Green-eyed Gecko 
Smooth chameleon 
Smooth Slug Snake 
Smooth Snake 
Smooth-backed Gliding Gecko 
Smooth-scaled Mountain Rat Snake 
Snake-eyed Lizard 
Snouted cobra 
Solomon Islands skink 
Sonora mud turtle 
Sonoran Desert Horned Lizard 
Sonoran Desert Sidewinder 
Sonoran Spiny-tailed Iguana 
Sonoran Spotted Whiptail