Hades

Hades (ハーデス, Hādesu) is a mythological deity and serves as the primary antagonist in the last story arc of Saint Seiya.

In the story, Hades is the ruler of the Underworld (冥界, Meikai) and old enemy of Athena. He wishes to wipe out humanity, turning the Earth into a desolate wasteland. He despises the human beings, who are each time more ungrateful towards the gods.

Avatars
In Saint Seiya, as in the Greek mythology, Hades is the Underworld god, and as such, incarnates into a human being. Every 243 years Hades can enter the world of humans, and fight against Athena for control over the world. However it is said that Hades is too fond of his own body which was born by Chronos and Rhea. He cares so much of it that he keeps it locked in a chamber in Elysion so it doesn't get damaged, only to start using it when he has taken control over the world. To fight the sacred wars against Athena, Hades has to take control of the purest human being born at the time of his incarnation. During the previous Holy War in 1747 his avatar was a boy named Alone, and now more recently it was Andromeda Shun.

Alone
In the 18th century, the avatar of Hades, Alone, was a close friend of the Pegasus Saint of that era (Tenma).

The Greatest Eclipse
After the Spectres were ordered back to the Underworld and Pandora's Castle collapsed, Hades waited in Giuddecca, knowing that his new avatar Shun would come. After Lyra Orphée was killed by Wyvern Rhadamanthys during a failed assassination of Hades, Shun became possessed and Seiya was thrown into Cocytus. Meanwhile, Ikki defeats Garuda Aiacos in the fifth prison. Hades senses his cosmo and orders Pandora to bring the individual. Ikki is warped to Giuddecca. There, he fights against Pandora and remembers he had already seen her once. Pandora tells him that the "Yours Ever" pendant she gave Shun years ago was the chain that tied him to Hades. Shun takes a brief possession of his own body and tells Ikki to kill him in order to destroy Hades and stop the Greatest Eclipse. However, Ikki wasn't able to do it, and was thrown into Cocytus by Harpy Valentine. Later, Athena and Virgo Shaka arrived; Athena asked him for a bargain: At the cost of her life, the Greatest Eclipse should stop. However, Athena's blood expels Hades from Shun's body. Enraged, Hades pulls Athena with him to Elysion.

Elysion
Seiya, Shun, Shiryu, Hyoga and Ikki reach Elysion. There, they fight Thanatos and Hypnos. However, after the twins are defeated, Hades wakes up in his own body. He fights the five Saints at once, receiving little damage to his Surplice. When Seiya asks why Hades' eyes are so sad, Hades sees Tenma in Seiya. Athena joins the battle and duels Hades. Seiya, trying to protect her, is mortally wounded by Hades' sword, and dies in front of Athena and his friends. Shun, Shiryu, Hyoga and Ikki concentrate their cosmos into Athena's Victory Staff. She throws her weapon into Hades and kills the underworld god.

Abilities and Attributes
Hades is one of the most powerful deities in the Saint Seiya Universe, being Zeus' brother. As the God of the Underwold, Hades can allow his specters to travel from the Underworld to the Living World, also, he can resurrect any living being at will (as he did with his deceased Specters, and Cerberus during The Lost Canvas series).

As usual, he uses an avatar when he returns to Earth, but it must be the purest soul on earth. Hades stores his mythological body and his Surplice in Elysion, and is kept in a marble tomb while defended by the minor deities Thanatos and Hypnos.

When the Bronze Saints attack his tomb, he returns into his body. Being a deity he is a possessor of the Big Will (Divine Cosmo) but, unlike his brother Poseidon in the Saint Seiya series, he could use all the power of his Divine Cosmo.