The violet-crowned hummingbird (Ramosomyia violiceps) is a hummingbird in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is found in Mexico and the southwestern United States.
The violet-crowned hummingbird is 10 to 11.5 cm (3.9 to 4.5 in) long . Both sexes of both subspecies have a bright red bill, sometimes with a black tip. Adult males of the nominate subspecies have an intense violet-blue crown, a bluish violet hindneck, and dull grayish brown to greenish brown back and rump. Their tail is coppery bronze. Their underside from throat to undertail coverts is pure white with light olive green flanks. Adult females are virtually identical, though in general somewhat duller overall. Males of subspecies R. v. ellioti are similar to the nominate. However, their crown is more turquoise blue and their tail greenish bronze. Females again are almost identical but duller.