The Violet-green Swallow, Tachycineta thalassina, is a small swallow.

Adults are velvet green on their upperparts with white underparts and a forked tail; they have white patches on the side of the rump. They are somewhat similar in appearance to the Tree Swallow. In adult males, the white throat area extends behind and above the eyes; adult females are duller in colour. Immature birds are brown on the upperparts.

Their breeding habitat is semi-open areas in western North America from Alaska to Mexico. They nest in cavities in a tree or rock crevice, sometimes forming small colonies.

They migrate in flocks to Central and South America.

These birds often forage in flocks, usually flying relatively high but sometimes flying low over water. They eat insects including mosquitos, butterflies, mayflies and moths.