The Irish Terrier was a vermin-catching family companion to rural (especially southern) Irish families for centuries.

In World War I, Irish Terriers were used as messengers, guard dogs, and companions to soldiers.

This breed is known for being fearless, partly due to its physiology being perfect for catching vermin; their long jaw seeks them out of hiding places, their big, sharp teeth catches them, and their small eyes surrounded by bone, protects them from bites.