A solar bird with much the same symbolism as the eagle; it is an attribute of all sun gods and represents the heavens; power; royalty; nobility.
Like the eagle, it was regarded as being able to fly up to the sun and gaze on it without flinching.
Gods with a hawk, or hawk-headed, are sun gods.
Aztec: A messenger of the gods.
Egyptian: The royal bird; the Spirit; the soul; inspiration; the Bird of Khensu; Ra, the sun. Other gods with hawks, or hawk-headed, are Ptah, Horus, Mentu, Rehu, Sokar, Kebhsenuf. The hawk-headed crocodile is Sebek-Ra; the sphinx is sometimes hawk-headed. The hawk is also an emblem of Amenti, Great Mother and goddess of the West and the underworld.
Graeco-Roman: The ‘swift messenger of Apollo’; attribute of Circe.
Hindu: Gayatri, the hawk, brought soma from heaven. The hawk is also a vehicle of Indra.
Iranian: An attribute of Ahura Maxza, or Ormuzd, as light.
Mithraic: An attribute of Mithra as sun god.
[Source: An Illustrated Encyclopedia of Traditional Symbols by J.C. Cooper]