Sontarans thrive on combat and delight in warfare. In their estimation no honour is greater than being killed in battle. Short, squat, muscular and grey, their leathery faces exude menace. They reproduce by cloning so are created in huge numbers, perfect for a race of soldiers literally born to fight.
They have one physical weakness—a small hole at the rear of their necks known as a "probic vent." A blow to this can stun or even kill a Sontaran but they believe it offers a kind of strength as it means they can never turn their back on opponents in battle.
Their enduring enemies are a shape-shifting race known as the Rutans but Sontarans will take on any species in battle. In the Fourth Doctor’s era they even attempted an invasion of Gallifrey itself. Their cunning and military genius meant they almost succeeded and although they were narrowly defeated they survived to indulge their passion for warfare throughout the universe.