The Jack Russell is a big dog in a small dog’s body. They are sturdy and tough, intelligent and brave with large personalities and they can be willful. Jack Russells are primarily working dogs and enjoy learning tricks, but they do need to be kept occupied and well exercised. Nipper the HMV dog is reputed to be a Jack Russell, but that’s debatable. Prince Charles, Goldie Hawn and Serena Williams all own Jack Russells.