Osarseph or Osarsiph is a legendary figure of Ancient Egypt who has been equated with Moses. His story was recounted by the Ptolemaic Egyptian historian Manetho in his Aigyptiaca (first half of the 3rd century BC); Manetho's work is lost, but the 1st century AD Jewish historian Josephus quotes extensively from it.
The story depicts Osarseph as a renegade Egyptian priest who leads an army of lepers and other unclean people against a pharaoh named Amenophis; the pharaoh is driven out of the country and the leper-army, in alliance with the Hyksos (whose story is also told by Manetho) ravage Egypt, committing many sacrileges against the gods, before Amenophis returns and expels them. Towards the end of the story Osarseph changes his name to Moses.
Also much debated is the question of what, if any, historical reality might lie behind the Osarseph story. The story has been linked with anti-Jewish propaganda of the 2nd and 1st centuries BC as an inversion of the Exodus story, but an influential study by Egyptologist Jan Assmann has suggested that no single historical incident or person lies behind the legend, and that it represents instead a conflation of several historical traumas, notably the religious reforms of Akhenaten (Amenophis IV).