SERAPIS sĕr’ ə pĭs (earlier Sarapis; Gr. from Egyp. Osir-Hapi, Osiris-Apis, sacred bull at Memphis). A Graeco-Egyp. deity whose cult was instituted by Ptolemy I (c. 323/04-285 b.c.) at Alexandria (the Serapeum).
Ptolemy I perhaps intended to unite his Egyp. and Gr. subjects in the worship of this god; but attained only limited success. As a Zeus-like figure, Serapis gained great popularity in the Graeco-Rom. world as a god of the afterlife, of fertility, of healing. He was a savior (e.g., of seafarers), giver of oracles and dreams, and linked with (or identified with) Helios, etc. To Egyptians, Serapis remained simply a form of Osiris, their god of the netherworld, fruitfulness, etc.
H. I. Bell, Cults and Creeds in Graeco-Roman Egypt (1953).