The Great Gray Owl (American English) or Great Grey Owl (British English) is a very large owl, documented as the world's largest species of owl by length. It is distributed across the Northern Hemisphere, and it is the only species in the genus Strix found in both Eastern and Western Hemispheres. In some areas it is also called Phantom of the North, cinereous owl, spectral owl, Lapland owl, spruce owl, bearded owl, and sooty owl.
In terms of length, the great grey owl is believed to exceed the Eurasian eagle-owl and the Blakiston's fish owl as the world's largest owl. The great grey is outweighed by those two species as well as several others, including most of the genus Bubo.