In Egyptian mythology, Sebek was the name of the crocodile-god, worshipped at the city of Arsinoe, called Crocodilopolis by the Greeks. Sebek was worshipped to appease him and his animals. According to some evidence, Sebek was considered a fourfold deity who represented the four elemental gods (Ra of fire, Shu of air, Geb of earth, and Osiris of water). In the Book of the Dead, Sebek assists in the birth of Horus; he fetches Isis and Nephthys to protect the deceased; and he aids in the destruction of Seth.
[Source: Shawn C. Knight, "Egyptian Mythology FAQ" ]