Owlet-nightjars are small, dusk-active birds primarily found in New Guinea with some species in Australia, the Moluccas, and New Caledonia; one flightless New Zealand species is now extinct. They belong to the single family Aegothelidae and genus Aegotheles. These insectivorous birds have camouflaging brown plumage, small weak feet (yet stronger than those of related nightjars and frogmouths), and very wide mouths with prominent whiskers. They have short wings and long, rounded tails. Eleven living species are recognized based on a 2003 study, and they are placed in a distinct order, Aegotheliformes, part of the larger clade Cypselomorphae, which includes the swifts and hummingbirds. Despite similarities to the caprimulgiform birds and superficially to small owls, owlet-nightjars are not as closely related to either. Their ancestors were widespread across Eurasia during the late Paleogene. Notably, fossil evidence in New Zealand from the Early to Middle Miocene period points to an ancient ancestor of these birds, with a new extinct species Aeotheles zealandivetus being described from this evidence in 2022.