Preah Ko (Khmer: ប្រាសាទព្រះគោ, "The Sacred Bull") was the first temple to be built in the ancient and now defunct city of Hariharalaya (in the area that today is called Roluos), some 15 kilometers south-east of the main group of temples at Angkor, Cambodia.

[1] Preah Ko (Sacred Bull) derives its name from the three statues of sandstone located in the front of and facing the temple's central towers.

When he ascended to the throne, he ordered the construction first of Preah Ko, which was dedicated in 879, and later of the temple-mountain known as the Bakong.

It is likely that this building program was made possible by the king's peaceful reign and his ability to draw income from the expanding empire.

The front central tower is dedicated to Jayavarman II, the founder of the Khmer empire.