Fell terrier is an old name for the long-legged working terriers of northern England's hill country, where shepherds needed small dogs that could follow foxes into rock crevices. The Patterdale, named for a Lake District village, is the best-known strain in the US, and the UKC recognized it in 1995. Listings often use both names for the same compact black, red or chocolate terrier with a smooth, broken or rough coat.
That working history shows at home. Many Patterdales have intense prey drive, plenty of stamina and a stubborn streak, and even the UKC standard says they aren't for the average pet owner. In SF, that means a firm leash routine on walks and a plan for mental work on rainy days. With patient, reward-based training, many become affectionate, funny companions for active people who enjoy a true terrier.