From Tolkien Gateway
Pascal Yung - Beorning Skin-changers

Skin-changers were creatures who could take different forms at will. Little is known of their abilities; the only famous skin-changers were Beorn and his descendants (who could take the shape of a Man or of a bear),[1] but evidently other skin-changers also existed.

It has been suggested that Radagast, a "master of shapes and hues", was able to change his form.[2]

See also