Bennu /ˈbɛnuː/] is an ancient Egyptian deity linked with the Sun, creation, and rebirth. He may have been the original inspiration for the phoenix legends that developed in Greek mythology. According to Egyptian mythology, Bennu was a self-created being said to have played a role in the creation of the world. He was said to be the ba of Ra and to have enabled the creative actions of Atum. The deity was said to have flown over the waters of Nun that existed before creation, landing on a rock and issuing a call that determined the nature of creation. He also was a symbol of rebirth and, therefore, was associated with Osiris.

Some of the titles of Bennu were "He Who Came Into Being by Himself", and "Lord of Jubilees"; the latter epithet referred to the belief that Bennu periodically renewed himself like the sun was thought to do. His name is related to the Egyptian verb wbn, meaning "to rise in brilliance" or "to shine".

New Kingdom artwork shows Bennu as a huge grey heron with a long beak and a two-feathered crest. Sometimes Bennu is depicted as perched on a benben stone (representing Ra and the name of the top stone of a pyramid) or in a willow tree (representing Osiris). Because of the connection with Osiris, Bennu sometimes wears the Atef crown, instead of the solar disk.

In comparatively recent times, a large species of heron, now extinct, lived on the Arabian Peninsula. It shares many characteristics with Bennu. It may have been the animal after which Bennu was modeled by the ancient Egyptians during the New Kingdom. 

Like Atum and Ra, the Bennu was probably worshipped in their cult center at Heliopolis. The deity also appears on funerary scarab amulets as a symbol of rebirth.

The Greek historian Herodotus, writing about Egyptian customs and traditions in the fifth century BC, wrote that the people at Heliopolis described the "phoenix" to him. They said it lived for 500 years before dying, resuscitating, building a funerary egg with myrrh for the paternal corpse, and carrying it to the temple of the Sun at Heliopolis. His description of the phoenix likens it to an eagle with red and gold plumage, reminiscent of the sun.

Long after Herodotus, the theme ultimately associated with the Greek phoenix, with the fire, pyre, and ashes of the dying bird developed in Greek traditions.

The name, "phoenix", could be derived from "Bennu" and its rebirth and connections with the sun resemble the beliefs about Bennu, however, Egyptian sources do not mention a death of the deity.