Costa's hummingbird (Calypte costae) is a bird species in the hummingbird family Trochilidae. It breeds in the arid region of the southwest United States and northwest Mexico; it winters in western Mexico.
Costa's hummingbird was formally described by the French ornithologist Jules Bourcier in 1839 and given the binomial name Ornismya costae. Bourcier chose the specific epithet to honour the French nobleman Louis Marie Pantaleon Costa, Marquis de Beauregard (1806–1864). The type locality is Magdalena Bay on the western coast of the Mexican state of Baja California Sur. Costa's hummingbird is now placed in the genus Calypte that was introduced in 1856 by John Gould. The species is monotypic: no subspecies are recognised.
Hybrids between this species and Anna's hummingbird, the black-chinned hummingbird as well as the broad-tailed hummingbird are known.