Ar-Pharazôn was the 24th, and last, King of Númenor. He ruled from SA 3255-3319. He was the son of Gimilkhâd, the younger brother of Palantír, the 23rd King.

As Pharazôn grew to manhood, the power of Palantír waned, and Pharazôn led the campaigns opposed to the Eldar-friendly reforms of Palantír. On Palantír's death, Pharazôn seized power from Míriel, the King's daughter and the Heir of the Sceptre. He declared himself the King, and forcibly married Míriel, changing her name to Ar-Zimraphêl.

Six years after Pharazôn seized the crown, he set sail for Umbar, aiming to challenge Sauron for the mastery of Middle-earth. Sauron was unable to contest the might of Númenor, and instead abased himself in front of Pharazôn, playing on that ruler's pride and begging mercy from him. Pharazôn then decided to take Sauron back to Númenor as a prisoner.

Sauron started to play on the Númenoreans obsession with the one prohibition laid on them by the Valar - their ban from the Undying Lands. He suggested to the King that the immortality which Pharazôn sought was in his grasp over at Valinor.

In 3310, when Pharazôn was an old man, he finally gave in to Sauron's wiles, and ordered a huge armada fleet to be built. In 3319, he set forth into the Western Seas with his Great Armament. What happened when Pharazôn's fleet reached Valinor is not certain, as none returned to Middle Earth to tell the tale. However his actions resulted in the destruction of Númenor by Ilúvatar, acting on prayers from the Valar.