Circe was a minor goddess of magic in Greek mythology, daughter of the Titans Helios, god of the sun, and Perse, an Oceanid. She had two brothers, Aeetes, who was the guardian of the Golden Fleece (which Jason and the Argonauts sought after), and Perses; and a sister, Pasiphae, who was the wife of Minos, king of Crete.
She is best known for her role in Homer's Odyssey. During their adventures towards Ithaca, Odysseus and his companions reached Colchys, where the residence of Circe was. She invited them all to a grand feast, which a lot of Odysseus' companions attended but not him. At the feast, one of the dishes was laced with a magical potion; when Odysseus' companions ate it, Circe made a quick move with her wand and turned them into pigs. Only one of the companions escaped unharmed and informed Odysseus. The hero, after taking advice from Hermes, protected himself from the spell by using a holy herb, and managed to befriend Circe and save his companions.
Another source mentions that Circe and Odysseus had three sons; Ardeas, Latinus, and Telegonus. In a lost epic called Telegony, Circe told Telegonus that his father was Odysseus (who had meanwhile returned to Ithaca and his wife, Penelope), and Telegonus went to find him. However, Circe gave him a poisoned spear, with which Telegonus mistakenly killed his father. Afterwards, he returned home along with Penelope and Telemachus, his half brother, and Circe granted them immortality.