Adults have a big, rounded head with a gray face and yellow eyes with darker circles around them. The underparts are light with dark streaks; the upper parts are gray with pale bars. This owl does not have ear tufts and has the largest facial disc of any raptor.
Their breeding habitat is the dense coniferous forests of the taiga, near open areas, such as meadows or bogs. Great Grey Owls do not build nests, so typically use nests previously used by a large bird, such as a raptor. They will also nest in broken-topped trees and cavities in large trees. Nesting may occur from March to May. Four eggs are the usual clutch size.