Serapis, Or Sarapis, an Egyptian divinity, whose worship prevailed in the reign of the Ptolemies. The name is supposed to be a compound of Osiris and Apis, or a conversion of the name Osir Hapi given to the dead Apis. The worship of Apis, but little developed in the time of the Pharaohs, became in another form of primary importance under the Ptolemies. According to Plutarch and Tacitus, Ptolemy I., warned by a dream, sent to Sinope for a colossal statue, which on its arrival at Alexandria was declared to represent the god Serapis. The temple Serapeum was built at Alexandria for the reception of the statue, and was the last hold of the pagans in that city after the introduction of Christianity. It was a magnificent structure, supported by arches, and divided within into spacious apartments. It was destroyed by the bishop Theophilus, by order of Theodosius, in 389; and "the colossal statue of Serapis was involved in the ruin of his temple and religion." Canopus was the seat of a shrine and oracle of Serapis. The worship of Serapis prevailed for a short time in Rome in A. D. 146, under Antoninus Pius, but was soon suppressed on account of its licentious character.

At Puteoli (Pozzuoli) there was a Serapeum, the ruins of which were uncovered in 1750, and are regarded as among the most remarkable remains of ancient architecture in Italy. In 1850 Mariette discovered the site of the Serapeum or Apis mausoleum at Memphis. It has now been completely unearthed. It is divided into three distinct parts; one served as the burial place of the sacred bulls from Amunoph III. of the 18th dynasty to the end of the 20th dynasty; another comprises the tombs of the Apis until the end of the 25th dynasty; and the third, which is the best preserved, those of the time till the later Ptolemies. Nearly 200 sphinxes have been laid bare, and the inscribed tablets which covered the walls, numbering about 500, have been removed to the Louvre.