Sphinx Pharaoh was the guardian of the Second Prison, and a celestial specter of Hades.
Pharaoh was who played his harp to Hades in various eras (in the anime). After Pandora's order, he uses the her mirror to disturbs Orphée's output. Orpheus stayed in the Meikai and in the anime, Pharaoh gets envy on Orphée because he stole his office.
He tries to kill Seiya and Shun, but Orphée did not allows this and instead feigns kiling the two. Pharaoh goes on to spy on Orphée and discovers that Shun and Seiya are still alive and catched Athena's cloth, and Orphée after discovering Pharaoh and Pandora have cheated him, Orphée fights against Pharaoh to avenge on him and recovers Athena's cloth.
During the musical fight, the G string of Orphée breaks, and with the mouth holding this string, Orphée play the Stringer Nocturne melody and kills Pharaoh.
Pharaoh was the guardian of the Lost Canvas's entry and tries kill Sisyphus with his Balance of Course, but was defeated by the Sisyphus attack.
His main attack (Ballance of Course) test the hearths of enemies, and after the hearth (removed of the body of the enemy) be heavier than a feather, the enemy is destroyed, and if the feather was heavier, Pharaoh can don't give the hearth back if he thinks the judgement was fake or wrought.