The rainbow-bearded thornbill (Chalcostigma herrani) is a species of hummingbird in the "coquettes", tribe Lesbiini of subfamily Lesbiinae.

[3][4] The rainbow-bearded thornbill was formally described in 1846 by the French ornithologists Adolphe Delattre and Jules Bourcier from specimens collected near the town of Pasto in southwest Colombia.

The specific epithet herrani was chosen to honor the Colombian general and statesman Pedro Alcántara Herrán.

Adult males of the nominate subspecies are mostly bottle green with a white dot behind the eye and rufous forecrown and crown.

Its gorget ("beard") is a rainbow of colors from celadon-green through turquoise to yellow and red at the lower end.

Adult females are generally similar to males, but with pale yellowish-ochre from lower the belly to the undertail coverts and a much reduced gorget.

Its primary habitat is paramo, open country with bushy patches and small woodlands, and gulleys with thickets of ferns and bromeliads.

It will chase off competitors for food sources, even if they are considerably larger (e.g. flowerpiercers) and will not tolerate other hummingbirds even on large fruiting trees.