Petosiris (Ancient Greek: Πετόσιρις),^[1][2] called Ankhefenkhons, was the high priest of Thoth at Hermopolis and held various priestly degrees in the service of Sakhmet, Khnum, Amen-Re and Hathor.

Petosiris was the son of Sishu and Nefer-renpet. He lived in the second half of the 4th century BCE, during the 28th Dynasty. In his tomb, located in the necropolis at Tuna el-Gebel, Petosiris prided himself on having re-established the fortunes of the temples in which he served.

There is a pseudepigraphic onomantic text, Petosiris to Nechepso, and it is possible that the priestly Petosiris described in this article is the inspiration for the attribution of authorship.^[3] Nechepso lived in the 7th century BCE and that the text is likely 2nd century BCE.