Welsh terrier, breed of medium-sized terrier developed in Wales more than a century ago. It stands about 15 in. (38 cm) high at the shoulder and weighs about 20 lb (9 kg). Its close-lying, harsh, wiry coat may be black and tan or black, grizzle, and tan in color. The direct descendant of the old English wirehaired black-and-tan sporting dogs from which have come many of the present-day terriers, the Welsh terrier was renowned for its gameness on badger, fox, and otter. In recent times it has been raised chiefly as a pet. See dog.