Carrion birds of the genus Corvidae who have a bad reputation in myth generally and in Tolkien's works in particular.

In The Hobbit many crows live in the Desolation of Smaug and Balin remarks that they are nasty and rude. In The Lord of the Rings  large crows appear, known as Crebain who act as messengers and spies for dark forces. They were much feared.