Phnom Dei is a 272 m high hill close to Siem Reap, Cambodia.
Phnom Dei is located to the southwest of the Banteay Srei, one of the major Angkorian temples, and south of Phnom Kulen. It is part of the temple complex in Angkor, the area that was the capital of the Khmer Empire.
There is a temple on top of the hill. It was built during the reign of King Yasovarman I (889-910 AD).
Phnom Dei is one of the hilltop temples built during the king's reign, the others being Phnom Bakheng, Phnom Bok and Phnom Krom.