Clione limacina, known as the naked sea butterfly, sea angel, and common clione, is a sea angel (pelagic sea slug) found from the surface to greater than 500 m (1,600 ft) depth. It lives in the Arctic Ocean and cold regions of the North Atlantic Ocean.

Clione limacina is the most abundant gimnosomate in the surface plankton of temperate and polar waters, becoming an important food source for whales and certain fishes.

The official name is Clione Limacina. It means the goddess of the sea like a slug. Clione is known as "the angel of drift ice" or "the fairy of drift ice", which is said to come with drift ice and leave with drift ice. It is translucent, has a red head and tail, and has spread wings, making it a mascot of the Sea of Okhotsk in winter.