The scylla is found in some medieval encyclopedias. It is a hybrid beast. It has the upper body of a woman and the lower body of a fish or serpent, a gaping mouth full of teeth, a belly like a beast and the tail of a dolphin. It is the enemy of sailors and all other humans.

The scylla is based on Scylla of Greek mythology. It was said to be a monster that lived on one side of a narrow strait, opposite the monster Charybdis that lived on the other side. Sailors who navigated the strait were in danger from both monsters; in trying to avoid one they would get too close to the other. Scylla is described as having the upper body of a woman and the lower body of a fish, with six dog heads around her waist, and sometimes multiple human heads on long necks.