An irresistible terror, Scylla lived across a narrow strait from the equally dangerous Charybdis. As with most tales from the past, the exact details differ, but most writers agree Scylla was once a woman and turned into a monster because of jealousy. Characteristics: Gorgeous yet terrifying. That’s how sailors of days’ past spoke of Scylla—a ferocious but irresistible monster of the sea. With snarling heads and tentacles and the face of a goddess, it’s easy to see why this was true.