Preah Khan  is a temple at Angkor, Cambodia, built in the 12th century for King Jayavarman VII. It is located northeast of Angkor Thom and just west of the Jayatataka baray, with which it was associated. It was the centre of a substantial organisation, with almost 100,000 officials and servants. The temple is flat in design, with a basic plan of successive rectangular galleries around a Buddhist sanctuary complicated by Hindu satellite temples and numerous later additions. Like the nearby Ta Prohm, Preah Khan has been left largely unrestored, with numerous trees and other vegetation growing among the ruins.

Preah Khan, meaning 'sacred sword', is a huge, highly explorable monastic complex, full of carvings, passages and photo opportunities. It originally served as a Buddhist monastery and school, yet it was more than just a monastery, it was an entire city enclosing a town of 56 hectares. About 100,000 farmers produced rice to feed about 15,000 monks, teachers, and students. For a short period it was also the residence of King Jayavarman VII whilst he awaited the re-construction of his permanent home in Angkor Thom. It is sprawling complex of infinite corridors and sensuous carvings, however many of the Buddha images were vandalised in the later Hindu resurgence, and some of the Buddha carvings in the central corridor have been crudely carved over with Bodhisattvas, and in a couple of odd cases, a lotus flower and a linga. Also to note are the many small holes in all the walls in the center of the building, it is said that originally every hole contained gold and diamonds which were stolen and resold by the Khmer Rouge.