This thesis analyses the figure of Arthur, in a period spanning the mid-nineteenth to mid-twentieth centuries, when that figure became increasingly protean and multifaceted, and the audience for the Arthurian legend grew in both size and variety. It argues that many authors wrote through Arthur, as well as about Arthur, using the figure to understand and test their own ideas about ideals (e.g. of manliness, kingship, or heroism) as well as problems (such as war, despotism, or ungodliness). This thesis analyses Arthur by considering him as a 'type', using a definition of the term that highlights a paradox: a type, in a scientific sense, is both perfect (an exemplary model) and normal (common enough to be representative). When applied to Arthur, it means that he is both a perfect, or near perfect, example, but is also to some extent a 'normal' human being. Different authors analysed in this thesis emphasise different aspects of the figure, according to whether they focus on Arthur's perfection or his normality. Other meanings of the word 'type' are also applied when relevant: the idea is not to force all versions of Arthur into a single or definitive category, but to retain the complexity of how Arthur is characterised and written about in texts. The ultimate aim of this thesis is to put the figure of Arthur into critical focus, and explain why he has been returned to so often in history.