Neptune (Latin: Neptūnus) was the Roman god of water and the sea. In the Greek-influenced tradition, Neptune was the brother of Jupiter and Pluto, each of them presiding over one of the three realms of Heaven, Earth and the Netherigions
Hades~ Ruler of the Underworld, god of wealth and the dead. He isn't considered an Olympian, however he is invited to Olympus whenever he wants. His three head dog, Cerberus guards his realm from intruders.