It has often been remarked that the Welsh warrior-king Arthur and the warrior-hero Fionn of the Irish tradition have similarities in character. Oliver Padel, in his Arthur in Medieval Welsh Literature, discusses briefly the similarity between the Arthur of the earliest Welsh literature and Fionn, noting that the Arthur of the early Welsh is “much closer to that of Fionn in Irish literature, or Robin Hood in medieval English ... as seen in these texts, Arthur and his men constitute a Welsh equivalent of an early Irish fían”. Similarities between the two heroes have been remarked upon by various scholars, but not explored in depth. Where it has been examined, by scholars such as Rebecca Shercliff and Kevin Murray, these examinations have been brief and have focused only on the earlier material. Furthermore, very little work has been done on the characterisation of Fionn in the Early Modern Irish material (that is, material written in early modern Irish, from around the 12th century onwards) and as a result his characterisation in this period is largely assumed to be the same as in previous centuries or to be ‘different’; but the extent to which it may be different is not discussed, nor is it given much attention. This thesis aims to fill that gap in scholarship, and to examine the characterisation of Fionn in this later material, alongside that of Arthur. This has helped to illuminate the status of these characters in this period, through a typological investigation unencumbered by genetic relationships. The first chapter focused on analysis of both characters through a discussion of their leadership and a terminological analysis of texts. This made it possible to better determine the roles that Fionn and Arthur were expected to be playing in their tales. Chapter 1 shows that Fionn was in some texts being presented as a king; of the fíanna and also over large swathes of Ireland. Additionally it shows that the role of Cormac mac Airt in the early modern texts was not as pronounced as had previously been thought. It also re-establishes Arthur as an Emperor or Chief lord as opposed to ‘king’ and examines his role as background or sedentary leader, questioning why he played so little a role in the texts which are famous for him having been in them, and what this means for his character. Chapters 2 and 3 examine Fionn and Arthur, respectively, within the context of courtly literature, and the virtues of pite, mesure, and largesce. It demonstrates that Fionn fits well within this context and frequently displays these virtues within the Early modern material. Comparatively, Chapter 3 demonstrates that Arthur does not fit so well within this courtly context as Fionn, and that his courtliness must instead be determined through analysis of his representatives; the knights of his court. This research shows that the differences between Fionn and Arthur in this period perhaps outweigh the similarities, and also that a typological analysis of the character of Fionn in the Early Modern period has shown to be beneficial to understanding further his characterisation at this point in time, as well as how he fits within the milieu of similar characters from the period.