The harbor (or harbour) seal, also known as the common seal, is found in coastal waters of the northern Atlantic and Pacific oceans, Baltic and North seas.

Harbor seals are brown, silvery white, tan, or gray, with distinctive V-shaped nostrils. Individual animals possess a unique pattern of spots, either dark on a light background or light on a dark. The body and flippers are short, and the head is rounded. As with other true seals, there is no pinna (ear flap).

Their global population is 400,000 to 500,000. Seal hunting, once a common practice, is now mostly illegal. While the species is no longer under threat as a whole, subspecies in certain habitats are threatened. Many local populations have been reduced or eliminated through disease, conflict with humans, and encounters with ocean litter.