Hogni
Hogni was the right-hand man to King Gunnar. When Gunnar was beaten in battle and captured, he said he would only tell his captors where his treasure was if they brought him Hogni's heart. At first, his captors brought him the heart of another man, but Gunnar said that this man's heart quaked too much to be Hogni's. Then his captors cut out Hogni's heart and Gunnar saw that that heart did not quake at all, and therefore must be Hogni's.
The Saga of the Volsungs. Translated by Jesse L. Byock. London: Penguin Books, 1990.