This article is about a subject that is from official sources but is not considered canon.
In their true form, selkies have black eyes, wrinkled grayish skin and sharp teeth. They come ashore and alter their appearance to blend in and interact with humans, with whom many selkies were capable of establishing long-term relationships.
Sam Winchester encountered selkies in his trip to the United Kingdom. What Sam thought initially as a small problem turned out to be a massive infestation of selkies posing as humans. Over time, the male selkies became uncontrollable and began to attack and destroy the town. They were eventually stopped when Sam called in Dean from the United States, and the brothers joined forces with a breaker named Emma (who was secretly a selkie herself).