Hades, known to the Romans a Pluto, is the greek god of the Underworld.
Hades was born as the first son of Cronus & Rhea, being born after Hera but before Poseidon. Like his siblings, he was eaten by his father, only to be regurgitated out thanks to Zeus.
He and his sibling fought against the Titans and emerged victorious after ten years. Hades and his brothers drew lots to decided who would rule what aspect of the world, with Hades getting the underworld.
Hades fell in love with his niece Persephone at first sight, deciding to make her his wife, Hades opened a tear in the earth directly below Persephone. The goddess fell in and fell all the way to the underworld. There, Hades was polite and courteous to the girl, a pleasant change from her overbearing mother, Demeter, and when he asked for her hand in marriage she agreed. However, angered by the kidnapping of her daughter, Demeter went to Zeus, demanding that he force Hades to return her. However, by this time, Persephone had already eaten the fruit of the underworld, which prevented her from leaving. Demeter, heartbroken at not being reunited with her daughter caused nature to whither and die, creating the first autumn, and eventually, the first winter. Seeing the damage Demeter' emotions were causing Zeus force Hades to accept a deal: Persephone would spend half of the year with Hades in the underworld, and the other half with Demeter on earth. When Persephone arrives on earth, Demeter's joy causes plants to grow, and when she returns to the underworld, Demeter's sorrow causes plants wither, hence the changing of the seasons began.
Despite ruling the underworld, Hades does not preside over death, with Thanatos being the greek god of death.
While Hades is often portrayed as evil in media, in greek mythology, he is actually one of the more altruistic gods.