Who is Anzu from Myths from Mesopotamia: Creation, the Flood, Gilgamesh, and Others and what is their importance?

Anzu is a lion-headed eagle. Ellil chooses Anzu as doorkeeper for his temple. In the myth, Anzu is depicted as the thief who steals the Tablet of Destinies and wreaks havoc, only to be stopped by Ninurta. The author, however, makes special note that Anzu is portrayed as benevolent and good in other Mesopotamian mythology.