The Lucifer Hummingbird, Calothorax lucifer is a medium-sized, up to 10cm long, green hummingbird with long decurved bill, small wings and white streak behind eye. The male has an iridescent plumage, forked dark tail, green crown, long magenta gorget and white underparts. The female is larger than male with duller plumage, pale throat and buff below.

The Lucifer Hummingbird is distributed to deserts and arid areas with agave plants in southwestern United States, from southwest Texas, New Mexico to extreme southern Arizona, and in central and north Mexico. It also found in the Madrean sky islands of the Sierra Madre Occidental, Mexico.

The diet consists mainly of nectar, spiders and small insects. The female lays two white eggs in the small cup-like nest.

A locally common species in its range, the Lucifer Hummingbird is evaluated as Least Concern on the IUCN Red List of Threatened Species.