Who was the Egyptian official who bought Joseph as a slave?

The Egyptian official who bought Joseph as a slave was Potiphar.

In Genesis, Joseph is sold by his brothers and taken to Egypt, where Potiphar purchases him. Potiphar is described as an officer of Pharaoh and captain of the guard. Joseph proves capable and is placed in charge of Potiphar’s household, but Potiphar’s wife attempts to seduce him.

Joseph refuses her advances and flees, leaving his garment behind. Potiphar’s wife then falsely accuses Joseph of attacking her. Believing the accusation, Potiphar sends Joseph to prison. That imprisonment eventually places Joseph near Pharaoh’s officials, allowing him to interpret dreams and begin his rise to power.

Potiphar is often confused with Potiphera, an Egyptian priest whose daughter Asenath later marries Joseph. Some traditions identify the two men, but Genesis presents them as different figures. For the specific question of who bought Joseph, Potiphar is the standard and unambiguous answer.