Scylla?

In Greek mythology, Scylla[a] (/ˈsɪlə/ ⓘ SIL-ə; Ancient Greek: Σκύλλα, romanized: Skýlla, pronounced [skýlːa]) is a legendary, man-eating monster that lives on one side of a narrow channel of water, opposite her counterpart, the sea-swallowing monster Charybdis. The two sides of the strait are within an arrow's range of each other—so close that sailors attempting to avoid the whirlpools of Charybdis would pass dangerously close to Scylla and vice versa. Scylla is first attested in Homer's Odyssey, where Odysseus and his crew encounter her and Charybdis on their travels. Later myth provides an origin story as a beautiful nymph who is transformed into a monster.