The bird genus Hirundo is a group of passerines in the family Hirundinidae (swallows and martins). These are the typical swallows, including the widespread Barn Swallow. Many of this group have blue backs, red on the face and sometimes the rump or nape, and whitish or rufous underparts. With fourteen species this genus is the largest in its family.
All of the species are found in the Old World, although one, the Barn Swallow, is cosmopolitan, also occurring in the Americas.
Genetic evidence has recently shown that many of the species previously included in Hirundo are less closely related than their appearance might suggest; these species are sometimes treated in the separate genera Cecropis (e.g. Red-rumped Swallow Cecropis daurica, previously Hirundo daurica) and Petrochelidon (e.g. Cliff Swallow Petrochelidon pyrrhonota, previously Hirundo pyrrhonota); they are as distinct from typical Hirundo as the House Martins in the genus Delichon.