Hecate

Hecate (Εκάτη in Ancient Greek) is the daughter of the Titans, Perses and Asteria. She is the goddess of magic, crossroads, trivial knowledge, and witchcraft. Her Roman Counterpart is Trivia.

History
Hecate was the Titan goddess of magic among many other things. Born to Perses and Asteria, Hecate was among the few Titans who supported Zeus and the Olympians in the Titanomachy and thus was allowed to retain her authority once the Olympians came into power. For her support, Zeus gave Hecate a share in all three realms of the cosmos for which she was known as the goddess of crossroads.

Hecate had little organized worship as she was more commonly found on the outskirts of the old myths than playing an active part in it. However, Hecate did play a major role in the abduction of Persephone. After her daughter's abduction, it was Hecate who told the frantic Demeter what had become of her daughter. After the dispute between her mother and husband was settled, Hecate became Persephone's confidante when she was in the Underworld. Thankful for their friendship, Hades honored Hecate as an prominent and permanent guest in the Underworld.

The Sea of Monsters
Hecate isn't shown, but is mentioned to be Circe's mother.

The Battle of the Labyrinth
Hecate doesn't appear but it is mentioned by Dionysus, that she has gone over to Kronos' side. She also sends her Empousai (Kelli and Tammi) to attack Percy.

The Last Olympian
It is mentioned that Hecate used her magic to cloak New York City and prevent mortals from entering or leaving. She also sends magical lights towards Mount Olympus, though the nature of these lights are unknown as the wards of Olympus repel them quickly.

At the end of the book, Hecate's cabin at Camp Half-Blood is under construction, along with those of many other minor gods. Her cabin is made of magical stones that, if dropped, could have disastrous effects.

The Heroes of Olympus
In The Lost Hero, it is revealed that Hecate is the mother of Lou Ellen.

Trivia (goddess)
Hecate can change her appearance and turn into her Roman counterpart, Trivia. As Trivia, she becomes more disciplined, warlike, and militaristic. Assuming that she and the other minor gods are honored at the Roman Camp Half-Blood, Trivia may have more children there. Hecate was envisioned by the Greeks as a mysterious and powerful being. To the Romans, Trivia was a darker and more sinister goddess.

Personality
A lover of solitude, Hecate's true nature is very much unknown. She spends a deal of time in the Underworld, being a close friend of Hades and Persephone especially. She apparently resented not being honored by the demigods since she supported Kronos in The Second Titan War. Since her children have been given their own place at Camp Half-Blood, she has given up her grudge against Olympus.

Physical description
Hecate does not appear in the series, and therefore is not physically described at all in the books. Hecate was usually depicted in Greek vase painting as a beautiful woman holding twin torches, dressed sometimes in a maiden's skirt and hunting boots much like her cousin, Artemis. In statuary Hecate was often depicted with three faces as the goddess of crossroads. Sometimes, Hecates was depicted with the faces of animals as well as humans and she is also sometimes shown in her dog´s company. In addition, she was also depicted as an elderly woman; the classic stereotype for witches.

Trivia

 * Despite her children in the book series, Hecate was a virgin goddess in most stories although her children may have been conceived in a way similar to Athena's children.
 * Trivia refers to obscure knowledge which Hecate/Trivia presided over.
 * Dogs are Hecate's sacred animal.
 * She is symbolized by twin torches and keys