Ar Pharazon was the Númenórean King who grew so powerful that he captured Sauron after defeating his armies. He was corrupted into the worship of Melkor / Morgoth, and launched the Númenórean Fleet in an assault on Valinor.
Recently Eru told Thalion Paurgiliath Arch Duke of Eltán that he is awake, and returning with his fleet, and we must prepare.