Crotalus mitchellii is a venomous pitviper species found in the Southwestern United States, and in northern Mexico. It was named in honor of Silas Weir Mitchell (1829-1914), a medical doctor who also studied rattlesnake venoms. Five subspecies are currently recognized, including the nominate subspecies described here.

Generally, this species does not exceed 100 cm in length, with large males measuring between 90 and 100 cm. The race on Angel de la Guarda Island is known to become larger, the maximum recorded length for a specimen there being 136.7 cm. In contrast, the population on El Muerto Island only reaches a maximum of 63.7 cm in length.

This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.

Found in the southwestern United States and in northwestern Mexico. In the United States, its range includes east-central and southern California, southwestern Nevada, extreme southwestern Utah and western Arizona. In Mexico it is native in most of Baja California, including Baja California Sur. It also inhabits a number of islands in the Gulf of California, including Angel de la Guarda, Carmen, Cerralvo, El Muerto, Espíritu Santo, Monserrate, Piojo, Salsipuedes, San José, as well as on Santa Margarita Island off the Pacific coast of Baja California Sur.