Find (Mod. Ir. Fionn; Arch. Ir. Vind; Celt. Vindos) son of Cumall, hero figure and central character of the Fianaigecht cycle, was almost certainly a euhemerised deity. A continental background for a deity of this name is well attested; he is commemorated in placenames such as Vienna (Wien < Vindobona). In Old Irish Historical literature he has close parallels with the seer-figure Find File, and it seems that the two were originally the same. He was adopted into the genealogical structures of the Laigin (Leinstermen), perhaps as early as the seventh century; his father is said to have been Cumall (or ‘Umall’; the meaning of the name is obscure), his mother is given as Muirne, daughter of a druid called Tadc son of Nuadu, and he is accorded a pedigree tracing him to the Laigin ancestors Nuadu Necht and Bressal Brecc.
Although earliest tradition appears to connect him with the Boyne valley, his ‘official biography’, as it took shape in a corpus of tales from the eighth century onwards, links him with the ritual site of Dún Ailinne (Knockaulin, Co. Kildare). This monument had close associations with the dynasty of Uí Fhailge at the dawn of the historical period (the sixth century?), and it may be significant that some of the stories represent his alleged father Cumall as a member of Uí Thairsig, a lineage of Uí Fhailge. It is possible, therefore, that this dynasty was responsible for his adoption and earliest development as a Leinster hero-figure.
In the Fianaigecht cycle, which reaches its most developed form between the tenth and twelfth centuries, Find features as leader of a warrior-band known as the Fianna. As a battle champion, he serves in turn the legendary kings Conn Cétchathach (qv), Cormac (qv) son of Art, and Cairpre Lifechair (qv). Stories featuring Find, some with pointedly supernatural themes, continued to be developed through the late medieval and early modern periods, and the entire body of tales concerning him is widely discussed by scholars of Irish literature and folk tradition. In later material, he is known as Finn McCool or MacCool .