Lassie is a rough collie, a long-coated dog breed of medium to large size that was originally used and bred for herding sheep in Scotland. The breed has since been bred for show and as a companion. Rough collies generally come in shades of sable and white, blue merle, tri-colored, and color-headed white. Lassie is a beloved fictional character who has starred in books, movies, radio, comic books, toys, and TV series for several decades. She is famous for her intelligence, courage, and undying loyalty.