Hecate was the Titan goddess of magic and witchcraft, among many other things, born to Perses and Asteria. Hecate was among the few ancient Titans who supported Zeus and the Olympians in the Titanomachy, and thus was allowed to retain her authority once the Olympians came into power. Zeus bestowed upon Hecate a share in all three realms of the world, underworld, sea, and sky, and was therefore able to cross most boundaries without hinderance, even going back and forth between the worlds of the living and the dead.
Hecate had little organized worship, and was more commonly found on the outskirts of the Olympian order than playing an active part in it. She was usually depicted as a beautiful woman having three human heads, though some images are much more fearsome (one with a snake's head, one with a horse's, and the third a boar's head).
Hecate did, however, play a major part in the abduction of Persephone. After her abduction, Hecate went and told the frantic Demeter what had become of her daughter. After the dispute between her mother and husband was settled, Hecate continued to play an important role in the life of Persephone, becoming her confidante when she was in the Underworld. Hades, thankful for their friendship, was more than hospitable, honoring Hecate as a prominent and permanent guest in the spirit world.
Not really known as a goddess of wisdom, Hecate is nevertheless recognized for a special type of knowledge.
Depictions of her range from a beautiful woman to an elderly "crone," much like the contemporary image of a witch.
A lover of solitude, Hecate was, like her cousin Artemis, an unmarried goddess. It is implied, however, that she does have children at Camp Half Blood. She is close friends with Persephone. Little else is known about her nature, including the reason she decided to aid the Titans in the Second Great War.
(someone put demigod powers here)