Old Jock (1859–1871), was a Fox Terrier famous during the late 19th and early 20th centuries. A mostly white dog, he ran briefly with a hunting kennel before becoming a show dog, most notably with a victory at the show which popularised the Fox Terrier. His main show rivalry was with a dog named Tartar, and along with a dog named Trap, the three were popular sires of the Fox Terrier breed. He was also involved in the early formation of the Jack Russell Terrier and the Dandie Dinmont Terrier breeds.