The barrow-wights are based on draugar, Norse ghosts who inhabit Viking graves and guard the treasures buried there. Draugar are incredibly strong and possess magical abilities, such as the power to shapeshift and control the weather. Their presence can also drive a mortal insane. When they have killed their victims they will often eat them or drink their blood. They can be harmed by iron, but it takes a hero to properly vanquish them, as told in Norse folklore. Stories such as Hervararkviða, an Old Norse poem from the Hervarar Saga in which the shieldmaiden Hervor visits a barrow ghost to reclaim a family sword, may have influenced Tolkien when creating his barrow-wights.