Who was HADES?

God of the dead, ruler of the Underworld, which was accordingly known as Hades. In various adventures, Hades abducted the maiden Persephone, tricked the heroes Theseus and Peirithous and managed to get himself handcuffed by Sisyphus.

The god Hades was a dread figure to the living, who were quite careful how they swore oaths in his name. To many people, simply to utter the word "Hades" was a frightening proposition. So they made up a euphemism, a word that meant the same thing but with a more pleasant sound.

Since all precious minerals came from under the earth (the dwelling place of Hades) and since the god was wealthy indeed when it came to the number of subjects in his kingdom of the dead, he was referred to as "Ploutos", wealth. This accounts for the name given him by the Romans, who called Zeus Jupiter, Ares Mars, Hermes Mercury and Hades Pluto.
--Taken from The Illustrated Encyclopedia of Greek Mythology

After overthrowing Cronus, Zeus, Poseidon, and Hades drew lots for shares of the world. Hades got the worst draw, and became the ruler of the Underworld. All the dead - good or bad - traveled to this land, guided by Hermes.

Hades is a greedy god, and was greatly concerned with increasing his number of subjects in the Underworld. He seldom left his kingdom, but did possess a helmet that could make him invisible.

Hades is also the god of wealth, as everything under the earth belongs to him. Subjects in his kingdom referred to him as "the rich one". He was the son Cronus and Rhea, and also the husband of Persephone. However, she only spends four months of the year with him.
--Taken from Greek Mythology

Links to information about the mythological HADES

http://en.wikipedia.org/wiki/Hades