Hades

The dark god of the dead, who ruled in the underworld, which also had the same name. His parents were Cronus and Rhea, and Zeus and Poseidon were his brothers. His queen was Persephone, who stayed with him six months of the year, thus causing the season on Earth to change to winter.
Hades was cold and without mercy, but was not considered evil. His hat made its wearer invisible, and Persus went to kill the Gorgons he used it.
The underworld was a dark and gloomy place, guarded by the three headed dog Cerberus, who gladly let the souls in but never let anyone out. It was divided into two parts: Erebus and Tartarus. The latter was the deepest cave, similar to the Christian hell, with many criminals being tortured forever: Tantalus, Sisyphus and Tityus were all suffering there.

Hades was considered a place were the practices of the living were repeated. The kings Minos, Rhadamanthus and Aeacos or the hero Triptolmus were the judges of the dead. Achilles was still the leader of his men, Agamemnon was strolling around sulking and Hercules shadow lived there, while the hero himself was celebrating forever amongst the gods.
To get to Hades the soul must pay the ferryman Charon to take it across the river Styx. Therefore, the Greeks were very careful about their funeral rituals and always made sure the dead would have a coin under his tongue to pay the ferryman. Otherwise the soul would have to wander aimlessly on the river's bank.
The Romans called Hades Pluto.