Scylla, daughter of Crataeis.
      Scylla Crataeis (or, Scylla the daughter of Crataeis), as told by Homer, was a sea-monster from birth, with six heads, containing three rows of teeth in each of her mouths, and twelve feet. Odysseus met her on his journey and lost six of his men to Scylla’s snatching mouths. Her parentage is often attributed to various deities (Phorcys, Hecate, Lamia, etc.) Scylla, in tandem with the whirlpool Charybdis, menaces the passage later identified in tradition as the Straits of Messina.
       In Hellenistic and, especially, in Roman literature, Scylla was depicted as a sea nymph romantically pursued by the sea god Glaucus. Ovid’s Scylla spurned Glaucus’ advances, and he sought aid from the titaness/witch Circe to make Scylla love him. Circe, who fell in love with Glaucus, in jealousy toward Scylla, transformed the sea nymph into a sea monster of epic proportions. Roman literary sources beginning with Vergil tell Scylla’s metamorphosis to a maiden with dogs girding her waist, the curse of Circe. In European iconographic tradition, Scylla is frequently depicted just before dogs assail her, i.e. as a maiden bathing in Circe’s poisoned water. Even in classical sources, but especially in the later tradition, Scylla is transformed into the foreboding headland at Castel Ruffo on the Calabrian side of the Messina Strait, a dangerous geological obstacle to passing sailors.
      NB: Scylla Crataeis is sometimes equated or conflated with the princess of Megara, also named Scylla (or, Scylla Nisi/Scylla the daughter of Nisus).
— RTM with Al G, Grace W, Katie J, Abby M


Further Reading:
G.M.A. Hanfmann (1987), “The Scylla of Corvey and Her Ancestors,” Dumbarton Oaks Papers 41:249-60. — JSTOR

Lexicon Iconographicum Mythologiae Classicae (1997) VIII.1.1137-45 s.v. "Skylla I", with plates at VIII.2 [Jentel, Marie-Odile].

Lexicon Iconographicum Mythologiae Classicae (2009) “Skylla I [addendum],” Supplementum 2009 1.453-57, with plates.

Hopman, Marianne Govers. 2012. Scylla: myth, metaphor, paradox. Cambrige University Press. — https://www.google.com/books/edition/Scylla/

Carbone, Marco Benoît. 2022. Geographies of Myth and Places of Identity: the Strait of Scylla and Charybdis in the modern imagination. London: Bloomsbury.


See also:
      Glaucus
      Odysseus: Scylla and Charybdis