The Lucifer hummingbird is 10-centimeter (3.9 in) long.

Small hummingbird with a long, curved bill. The male is dusky-greenish with a contrasting white chest, expansive purple throat, and long forked tail (usually held closed in a point). The female is buffy below with a dusky mask and buffy eyebrows. All ages and sexes are most easily identified by bill shape. Found in deserts; shows a preference for flowering agave plants. The male Lucifer has pointed outer tail feathers vs. blunt on Beautiful, but otherwise essentially inseparable.

Distributed to deserts and arid areas with agave plants in the southwestern United States, from southwest Texas, and extreme southwestern New Mexico to southeastern Arizona, and in central and northern Mexico. It is also found in the Madrean sky islands of the northern end of the Sierra Madre Occidental, Mexico. Its preferred habitat tends to be at altitudes of 3,500–5,500 feet (1,100–1,700 m) in canyons, mountain slopes, and dry washes having desert shrubs and cacti. In winter, the birds migrate to central Mexico.