Scylla

In Greek mythology, Scylla 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.