The harp seal belongs to a group of mammals known as pinnipeds (meaning feather-, fin-, or web-footed), which includes the true seals, fur seals, sea lions and walruses. 

The harp seals common name comes from the black, wish-bone shaped marking found on the back of the adult, which presumably someone once thought looked like a musical harp (Lavigne and Kovacs 1988). The harp seal is also sometimes referred to as the saddle-backed seal, for obvious reasons.

The harp seals scientific name, Pagophilus groenlandicus, means "the ice-lover from Greenland." It is also known as Phoca groenlandica, which means simply "the Greenland seal."