Ettins were a type of giant that lived in the most northern land of the world of Narnia (which was eventually named Ettinsmoor). They were generally violent and unintelligent and can be described to either having two heads or four arms, but never both.
These creatures were once civilized ones that built ancient cities and bridges around the Wild Lands of the North during the Age of Conquest. But worse, during the Age of Winter, they all started to become uncivilized and became violent with stupidity and vicious temperament.
During 1014, the Ettins raided areas at the northern edge of the Narnian Empire. The Narnian King Peter declared war against the Ettins where they fought them in the Ettinsmoor War. Centuries later after Caspian X became king of Telmar and Narnia, Ettins were again entering on the Narnian territory. Caspian X along with the Telmarines and the Old Narnians working together, all fought against these creatures in 2304 and forced them to leave.
Before the Ettinsmoor War, some Ettins traveled to Narnia to become loyal to the White Witch where they served in her army to fight in the First Battle of Beruna against Aslan's army, The Lion, the Witch, and the Wardrobe. One Ettin named Pire who was a threat to Archenland, fought against a brave king named Olvin. Olvin managed to defeat Pire and later turned him into a mountain.