(Part of the) common name of all species of the families Strigidae and Tytonidae (order Strigiformes), which are the world-wide nocturnal counterparts of the diurnal birds of prey. They are in general soft-plumed, short-tailed, big-headed birds with both eyes directed forwards and surrounded by a facial disk and a very freely movable head (> 180°). The Strigidae family (over 120 species) comprises the typical owls with a circular facial disk and rather strong, usually thickly feathered, legs. The Tytonidae (10 species) or 'barn owls' have heart-shaped facial disks and long slender legs, and are mostly strictly nocturnal.

Alternative forms for owls : Aegolius, Asio, Athene, Bubo, Glaucidium, Nyctea, Otus, owl, Strix, Surnia, Tyto.