Patriarch Peter II of Alexandria (; died 27 February 381) was the 21st Patriarch of Alexandria from AD 373 to AD 381. He was a disciple of Athanasius of Alexandria who designated him as his successor before his death in 373.
The Arians opposed his appointment and shortly after his consecration, the prefect Palladius, acting on orders from Emperor Valens drove him from the city and installed Lucius, an adherent of Arianism as bishop. Pope Damasus I, hearing of this new persecution, sent a deacon with a letter of communion and consolation for Peter; the messenger was arrested, treated as a criminal, savagely beaten, and sent to the mines of Phenne.
Peter died around 380 and was succeeded by his brother Timothy.