The argument of this thesis is twofold. Firstly, it is to show that from the eighteenth century onwards Scottish scholars and writers have made a distinct and important contribution, hitherto mostly unnoted, to the dissemination of Old Norse history and literature in Britain. Furthermore Scottish writers such as Samuel Laing, Thomas Carlyle, and R.M. Ballantyne played a significant role in the creation of the literary notion of a Norse ethos which was to be a central point in the literary and journalistic debate in Scotland between c.1880 and 1940 on the relative merits of opposing Norse and Celtic influences on Scottish history, culture and society. Secondly, and more particularly, the thesis illustrates how this consciousness of a literary and historical Norse heritage in Scotland influenced many minor authors in Orkney and Shetland, and eight important Scottish writers in the twentieth century: Lewis Grassic Gibbon, Hugh MacDiarmid, Neil M. Gunn, John Buchan, David Lindsay, Naomi Mitchison, Eric Linklater, and George Mackay Brown. The thesis examines in detail the Norse-inspired works of these writers and investigates how and why they became influenced by Old Norse history and literature, what sources they used, and what effect this had on their work. The Old Norse influence is mostly notable in the writers' attitudes to the Norse/Celtic debate, their use of saga and skaldic styles, their knowledge and application of Viking history, their interpretation and use of Old Norse mythology, and a belief in atavism and contemporary applications of a Norse ethos. The nature of this influence on each individual author varies both in extent and form, but its existence and relevance cannot be questioned, and the thesis argues that this Old Norse influence has thus played an interesting and significant role in modern Scottish literature.