Crotalus willardi is a venomous pit viper species found in the southwestern United States and Mexico.

[6] The specific name, willardi, is in honor of its discoverer, "Professor" Frank Cottle Willard, a businessman from Tombstone, Arizona.

Color patterns are generally a dark brown base with pale or white horizontal striping, but vary slightly among subspecies.

Rattlesnakes are primarily ambush hunters; they coil and lie waiting for prey to approach within striking distance.

Contrasting with viviparous animals, the young still develop within an egg inside the female snake until their time of birth.

No documented deaths have been caused by ridge-nosed rattlesnakes, but pain and discomfort can still result from a rare bite.