Neptune

Neptune is a gas giant in the Solar System. Neptune appears similar to Uranus. It is dark blue in color.

Beast Wars II cartoon
One of Neptune's moons was devoured by Nemesis on its way to Gaea.

Sailor Moon
Neptune (海王星; Star of the Ocean's King) is the eighth planet from the Sun in this Solar System. It has 13 known moons, but the largest is Triton. It is grouped with Jupiter, Saturn, and Uranus as a planet of the outer Solar System.

In the Sailor Moon series, Neptune was protected by Sailor Neptune, even though in the present she resided on Earth with the other Sailor Senshi of the system. During the time of the Silver Millennium, Sailor Neptune remained there alone.

In the manga, Triton Castle orbited Neptune, and was the palace of Princess Neptune.

Mythology
Neptune, also known as Poseidon in the Greek pantheon, was the god of water and the sea. He was the son of Saturn and Ops, and the brother of Jupiter and Pluto. Neptune was often associated with horses.

Astrology
Neptune is associated with idealism, imagination, self-sacrifice, spirituality, creativity, sensitivity, and compassion.

Trivia

 * It is the smallest of the 4 gas giants
 * It has the fastest winds in the solar system
 * It has a "Great Dark Spot" similar to Jupiter's "Great Red Spot"
 * It has 13 moons, the biggest being Triton