Cabeza de Vaca, Álvar Núñez (äl'vär nOO'nyāth käbā'thä dā vä'kä) [key], c.1490–c.1557, Spanish explorer. Cabeza de Vaca [cow's head] was not actually a surname but a hereditary title in his mother's family; he is frequently called simply Álvar Núñez.
