The Stygian owl (Asio stygius) is a medium-sized dusky colored owl. It has yellow eyes, a black beak, a dark blackish facial disk, and white eyebrows. Its underparts are a dingy buff color with dark brown barring and streaks. The upperparts are reverse, buff barring and streaks on a dark background. This owl occupies a variety of deciduous and evergreen forests, and open areas with patchy forest. It lives from sea level to 3,100 metres (10,200 ft) above. This species takes in a variety of prey including birds, small mammals, reptiles, amphibians, crustaceans, and insects. All of its hunting is done at night.
The Stygian owl lays two eggs in stick nests created by other birds, but occasionally, they will nest on the ground, like their relative, the short-eared owl.
The adjective Stygian means "of, or relating to, the River Styx", but is more widely applied to anything that is dark or dismal.