Horwennefer (Ancient Egyptian: ḥr-wnn-nfr "Horus-Onnophris"; Ancient Greek: Άροννώφρις Haronnṓphris) was an Egyptian who led Upper Egypt in secession from the rule of Ptolemy IV Philopator in 205 BC. No monuments are attested to this king but along with his successor, Ankhwennefer (also known as Chaonnophris or Ankhmakis), he held a large part of Egypt until 186 BC. Contemporary accounts suggest that Horwennefer was a Nubian. A graffito dating to about 201 BC on a wall of the mortuary Temple of Seti I at Abydos, in which his name is written Ὑργοναφορ (Hyrgonaphor), is an attestation to the extent of his influence and the ideology of his reign. He appears to have died before 197 BC.
The Abydene graffito, one of the few documents remaining from his reign, is written in Egyptian using Greek letters, the oldest testimony of a development which would end in the Coptic script replacing the native Egyptian demotic.
