Serapis was an Egyptian deity whose name was adopted by the Greeks during the Hellenistic period in Egypt. 

Originally a god of the underworld, Serapis was represented in the Serapeum at Alexandria, the largest of the temples dedicated to him, as a robed and bearded figure regally enthroned, his right hand resting on Cerberus (the dog guarding the gate of the underworld), while his left hand held an upraised sceptre.

  Serapis was revered as a sun god and also lord of healing and of fertility.  Among the Gnostics he was a symbol of the universal godhead. 

The Serapeum at Saqqarah originated as a monument to the deceased Apis bulls, sacred animals of the god Ptah.  This temple was both a catacomb and a shrine to the Apis who in death became associated with the god Osiris as Osiris-Apis.  The Greeks living near Saqqarah worshipped this god as Osorapis, which later became Serapis.

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