The Íslendingasögur, written in Iceland in the thirteenth and fourteenth centuries, primarily describe the lives of Icelanders during the tenth and eleventh centuries. Many of these lives involve encounters with foreign peoples, both abroad and in Iceland, who are portrayed according to stereotypes which vary depending on the origins of those people. Notably, inhabitants of the places identified in the sagas as Írland, Skotland and Vínland are portrayed as being less civilized than the Icelanders themselves. This thesis explores the ways in which the Íslendingasögur emphasize this relative barbarity through descriptions of diet, material culture, style of warfare, and character. These characteristics are discussed in relation to parallel descriptions of Icelandic characters and lifestyle within the Íslendingasögur, and also in the context of a tradition in contemporary European literature which portrayed the Icelanders themselves as barbaric. Innovatively, comparisons are made with descriptions of barbarians in classical Roman texts, primarily Sallust, but also Caesar and Tacitus. Taking into account the availability and significance of classical learning in medieval Iceland, the comparison with Roman texts yields striking similarities between Roman and Icelandic ideas about barbarians. It is argued that the depiction of foreigners in the Íslendingasögur is almost identical to that of ancient Roman authors, and that the medieval Icelanders had both means and motive to use Roman ideas for inspiration in their own portrayal of the world. Ultimately it is argued that when the medieval Icelanders contemplated the peoples their Viking Age ancestors encountered around the world, they drew on classical ideas of the barbarian to complement the mix of oral tradition, literary inspiration and contemporary circumstance that otherwise form the Íslendingasögur.