Cú-Chulainn is among the best-known figures of early and medieval Irish heroic literature and is the central character of ‘Táin Bó Cuailnge’ and other tales of the Ulster cycle. His exploits as leader of the Cráeb Rua (Red Branch) warrior band would make him contemporary with Conchobar (qv) son of Ness, king of Ulster, whose reign is synonymous with the glories of Emain Macha, which medieval Irish pseudo-historians associated with a distant past. According to the Ulster tales his father was Soaltach or Sualtaim, a warrior of Emain Macha; his mother, Deichtine, was sister of Conchobar. He was allegedly fostered by Finnchaem, another of the king's sisters, and her husband the poet Amargein; their son was Conall Cernach (qv), with whom Cú-Chulainn was raised. Tradition assigns Cú-Chulainn several wives or partners, including Emir daughter of Fergal Manach and Eithne Inguba. A daughter of Cú-Chulainn, Finscoth, supposedly married Erc son of Cairpre Nia Fer, an early ancestral figure of the Laigin.
The place of Cú-Chulainn in literature and his embodiment of the warrior ideal have been widely discussed. There are a number of tales concerning his boyhood deeds, most notable being that which outlines how he got his name by killing the hound (cú ) of a blacksmith called Culann. Another recounts how, as a young man, he foiled the malicious designs of the courtier Bricriu, demonstrating such bravery that he earned the ‘hero's portion’ at a feast given by his protagonist. Perhaps the best-known, and oldest, story of Cú-Chulainn tells of his part in the war against Medb Chruachna (qv) – who almost certainly personifies a goddess, but is represented as queen of Connacht. Single-handedly, he defended the Gap of Ulster, standing his ground to the death so that the Ulstermen would have time to organise their forces.
It is significant that literary tradition accords him semi-divine status; his boyhood name Sétanta, reflected in the north-British tribe of the Setantii, seems to indicate a role as ancestral deity. More explicit is the role assigned, in some stories, to the deity Lug as his ‘otherworld patron’. It has been suggested that the tradition of Cú-Chulainn, whose name also perhaps conveyed the sense of ‘chariot warrior’ (cú also meaning ‘warrior’ and cul being an archaic word for ‘chariot’), had its origins among British or Gaulish settlers in Ireland, several figures with whom he is brought into contact having British or Gaulish associations. Irish genealogical tradition, however, furnishes Cú-Chulainn with a pedigree and meticulously details his alleged family, representing him as ancestor of the relatively unimportant Corcu Caullain and Dál Cualni among the Cruithni. Stories of Cú-Chulainn feature in the folklore of Ireland (especially in Ulster and Connacht) and in that of Scotland, including some oral tales for which there are no surviving written exemplars.