The West Coast garter snake (Thamnophis validus) is a species of snake in the family Colubridae. The species is endemic to Mexico. Four subspecies are recognized.
T. validus is found in the Mexican states of Baja California Sur, Chihuahua, Guerrero, Jalisco, and Sonora.
T. validus is viviparous.
There are four subspecies of T. validus which are recognized as being valid, including the nominotypical subspecies.
Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Thamnophis.
The subspecific name, isabelleae, is in honor of American wildlife artist Isabelle Hunt Conant, the wife of American herpetologist Roger Conant.