His first appearance was in the Golden Age comic Venus #3, or possibly Kid Komics #1.
Neptune is the god of the sea and he is Zeus's older brother. Zeus is probably the only Olympian god who is more powerful than Neptune. Neptune rules the seas and he is Hercules's uncle. He was the son of Kronos and Rhea. He was usually represented as carrying a trident and accompanied by dolphins. His carriage was a huge shell, drawn by horses or sea-horses.
Neptune is the patron god of the aquatic Atlanteans. When mortal worship of the Olympians faded and the gods withdrew from the Earth, Neptune alone remained actively worshiped by his chosen mortals. Atlanteans believe Neptune created their water-breathing race 10,000 years after the Great Cataclysm. When Atlanteans started worshiping Set approximately 2000 years ago, Neptune fought and banished Set. Afterwards, Neptune lived among the Atlanteans for a time, and left a copy of his trident with their ruler upon his departure.
Powers and Abilities
Neptune's powers are only rivaled by one Olympian god which is Zeus. Neptune has superhuman strength equal to that of Zeus, he has super speed, godlike agility and stamina which makes him tireless, has a great resistance to physical injury probably greater than Hercules's and has invulnerability to many physical attacks and he does not get harmed by conventional weapons. He can control, create and manipulate water such as making an entire ocean into a puddle, creating tsunamis, destroying entire cities with the sea, flooding the army of Mikaboshi, creating a dimension out of a drop of water and creating tidal waves that can overpower the Hulk with one strike of his trident. He can also manipulate energy and blast water and energy blasts, and has divine powers which allow him to resurrect the dead. He can create powerful electrical fields and can create force fields powerful enough to protect him from Zeus's attacks. He has the power of flight, can breathe under water for eternity, can breathe oxygen as well and is the greatest swimmer in the earth. He can create and blast mystical bolts or generate blasts powerful enough to be at a planet destroying level. Neptune is nearly omnipotent like Odin and Zeus, allowing him to banish the faceless ones with a wave of his hand He possesses power great enough to destroy a small statue of Set instantly with one tremendous blow of his trident, which also killed all the other people in the room save for Ossem, as they were Set's followers. He also has the power of weather control, light absorption, electric disruption and astral projection, can control some of the cosmic energies in the universe, can control fire and can withstand high temperatures up to the core of a star 10 million times the size of our sun and temperatures below absolute zero.
Weapons and Equipment
Neptune carries a Trident forged by the cyclopes that was made from his essence and is a symbol of his power. The cyclopes also forged Zeus' Thunderbolt and Pluto's Helm. Neptune's Trident is virtually indestructible as it is composed of the godly substance, adamantine. Independent of Neptune, the Trident can control the waters of the Earth, conjure massive amounts of water, and manipulate energy for various purposes (including bolts, arcs, and forcefields), as well as control all sea animals. The Trident has been used by Neptune and his champion, Namor.