Tornjak ("tor" is Bosnian and Croatian for corral/sheepfold) is a dog breed native to Bosnia and Herzegovina and Croatia. It is a mountain sheep dog. The Tornjak typically has stronger bones, and a better highlighted difference between the sexes. Tornjaks are large dogs with long hair in different colors; they are dogs with protective instinct, exceptionally gentle and careful with children. Like all other shepherd dogs they are devoted to their family (their human pack), distrustful and reserved towards unfamiliar.

A canon from Ðakovo who was the manager of the bishop's estate in Ðakovo, Petar Lukic, wrote in his reports from 1752 about a Croatian mountain dog 4 to 5 palms tall (60 to 75 cm), with different colors that could be black, grey, yellow, brown and red or combined with white. Some have as many as three colors.

The ears hang down and the tail is cover with thick hair. The Tornjak is mainly used for defending livestock (but also people) from wild beasts, particularly wolves.

This dog is mostly bred in the mountain parts, which is the reason why they are sometimes called "Canis montanis", or mountain dog.

On February 24, 2006, this breed was recognized by the Fédération Cynologique