Largest owl ever

The largest owl of all time was the Cuban giant owl Ornimegalonyx, which is known from fossils of four closely related species all native to Cuba and dating from the late Pleistocene epoch, 10,000 years ago. Standing 1.1 m tall, and probably weighing well in excess of 9 kg, it is believed to have been flightless or almost flightless, and had proportionately long legs.