King of Munster in the context of Cerball mac Dúnlainge

Deda mac Sin (Deda, son of Sen) was a prehistoric king of the Érainn of Ireland, possibly of the 1st century BC. Variant forms or spellings include Ded, Dedu, Dedad, Degad, Dega, Dego, Deguth and Daig, with some of these occurring as genitives although usage is entirely unsystematic, besides the rare occurrence of the obvious genitive Dedaid.

He is the eponymous ancestor of the Clanna Dedad, and may also have been a King of Munster.

Eóganacht Chaisil were a branch of the Eóganachta, the ruling dynasty of Munster between the 5th and 10th centuries. They took their name from Cashel (County Tipperary) which was the capital of the early Catholic kingdom of Munster. They were descended from Óengus mac Nad Froích (died 489), the first Christian King of Munster, through his son Feidlimid mac Óengusa.

In the seventh century, they split into two main clans. Cenél Fíngin descended from Fíngen mac Áedo Duib (d. 618) and became the O'Sullivans and MacGillycuddys. The McGillycuddy are a sept of the O'Sullivan's. A descendant of Fíngen was Feidlimid mac Cremthanin (d. 847). Clann Faílbe descended from Faílbe Flann mac Áedo Duib (d. 639) and became the MacCarthy dynasty, rulers of the Kingdom of Desmond following their displacement by the Normans. The O'Callaghans belong to the same line as the MacCarthys, while the MacAuliffes are a sept of the MacCarthys.

Faílbe Flann mac Áedo Duib (died 639) was a King of Munster from the Eóganacht Chaisil branch of the Eoganachta. He succeeded Cathal mac Áedo Flaind Chathrach of the Glendamnach branch in 628. He was the younger brother of a previous king Fíngen mac Áedo Duib (d. 618). His sobriquet Flann meant "blood-red".

Brian Boru (Middle Irish: Brian Bóruma mac Cennétig; modern Irish: Brian Bóramha; c. 941 – 23 April 1014) was the High King of Ireland from 1002 to 1014. He ended the domination of the High Kingship of Ireland by the Uí Néill, and is likely responsible for ending Viking invasions of Ireland. Brian Boru is mentioned in the Annals of Inisfallen and in Chronicon Scotorum as "Brian mac Cennétig" (Brian, son of Cennétig). The name Brian of Bóruma or Brian Boru was given to him posthumously. Brian built on the achievements of his father, Cennétig mac Lorcain, and especially his elder brother, Mathgamain. Brian first made himself king of Munster, then subjugated Leinster, eventually becoming High King of Ireland. He was the founder of the O'Brien dynasty, and is widely regarded as one of the most successful and unifying monarchs in medieval Ireland.

With a population of under 500,000 people, Ireland had over 150 kings, with greater or lesser domains. The Uí Néill king Máel Sechnaill mac Domnaill, abandoned by his northern kinsmen of the Cenél nEógain and Cenél Conaill, acknowledged Brian as High King at Athlone in 1002. In the decade that followed, Brian campaigned against the northern Uí Néill, who refused to accept his claims; against Leinster, where resistance was frequent; and against the Norse-Gaelic Kingdom of Dublin. Brian was described in the Annals of Ulster as ardrí Gaidhel Erenn & Gall & Bretan, August iartair tuaiscirt Eorpa uile (High King of the Gaels of Ireland and the Norse foreigners and the Britons, Augustus of all north-western Europe), the only Irish king to receive that distinction in the annals.