Circe is a sorceress who lives on her own island. When Odysseus visited, he lost his entire crew, but Circe told him how to get home to Ithaca.
The second time Poseidon sent Odysseus's ship off course, it ended up at Circe's island. The crew went ashore, leaving Odysseus to deal with the ship's anchor. When they got to Circe's house, she emerged, welcomed them to her island and introduced herself. Moe remarked (in an aside to Lenny), "Who decided to give every weirdo an island?" Circe then said that the crew must be thirsty and invited them to drink from her cauldron, which was filled with a bubbling green fluid and surrounded by skeletons holding goblets. The crew callously pushed the skeletons aside, grabbed the goblets, dipped them into the cauldron and had a drink. As soon as they drank, they were transformed into pigs.
Just then, Odysseus finally arrived and sarcastically said, "Thanks for your help with the anchor, guys!" He saw the pigs, realized he was hungry, picked one up and took a bite—undeterred either by the fact that the pig looked just like Lenny or by its protesting in Lenny's voice as he bit into it. Hours later, he had eaten all the pigs, in spite of Circe's repeatedly telling him that they were his crew. When he finally realized what had happened, he said he wanted to go home to Ithaca and asked Circe which way it was. Circe gave him directions, but warned him it wasn't that easy: "You must first go through Hades, crossing the River Styx."
She is voiced by Tress MacNeille.