Báetán mac Cairill
Báetán mac Cairill, (died 581), was king of the Dál Fiatach, and high-king of Ulaid, from circa 572 until his death. He was the son of Cairell mac Muiredaig Muinderg (died 532) and brother of Demmán mac Cairill (died 572), previous Kings of Ulaid. According to some sources, he was high-king of Ireland.
Báetán sought to impose his authority over Dál Riata in Scotland, and over the Isle of Man. Medieval Ulster genealogists describe him as rí Érenn ocus Alban (king of Ireland and Scotland), and quote from a poem, now lost, which has him receiving tribute from Munster, Connaught, Skye and the Isle of Man. This is probably to overstate his power, and represents what it meant to be high-king in much later times, rather than in Báetán's day.
Báetán is said to have forced the king of Dál Riata to pay homage to him at Rinn Seimne on Islandmagee near Larne, modern County Antrim possibly in 574 or early 575. Áedán mac Gabráin is thought to be the king in question, and Ulster sources say that Báetán collected tribute from Scotland. Báetán's power can best be judged by actions of his enemies, Áed mac Ainmuirech of Northern Uí Néill and Áedán mac Gabráin of Dál Riata. In 575, at Druim Cett, these two met and made an alliance, fostered by the future Saint Columba, a member of the Cenél Conaill like Áed, to oppose Báetán's attempts to increase his power by extending Dál Fiatach influence beyond the isle of Ireland.
The Annals of Ulster record an expedition of the Ulaid to the Isle of Man in 577 and their return in 578 in which Báetán imposed his authority on the island. In 582 after his death, the annals record the taking of Man by Áedán mac Gabráin.
Báetán was unable to achieve his ends, but he was not be the last king of the Ulaid to seek conquests and allies overseas. Fiachnae mac Báetáin of the Dál nAraidi would follow the same path in the 620s and Congal Cáech in the 630s.
Báetán was married to a woman of the Ui Tuitre (a tribe of the Airgialla west of Lough Neagh in modern County Tyrone) with whom he may have had an alliance. Báetán's descendants did not hold the kingship which became the monopoly of his brother's descendants, the Clan Demmáin. His sons were killed by their cousin Máel Dúin mac Fiachnai. This is recorded in the annals in the year 605 where it is said they were slain by their uterine brother.
- Annals of Ulster AU 581.2; 587.3; Annals of Tigernach AT 579.3
- Byrne, Table 6; Charles-Edwards, appendix XXI; Mac Niocaill, pg.74
- Byrne, pp. 109–111, 285
- Byrne, pp. 109–110.
- Byrne, pg.110; Ó Cróinín (EMI) ,pg.50; Mac Niocaill, pg.77; Ó Cróinín (NHI), pg.216
- Byrne, pp. 109–110; Ó Cróinín (EMI), pp. 50– 51. See also Adomnán, Life, notes 84 & 204, where Sharpe argues for a date later than the 575 reported by the annals.
- AU 577.6; 578.2; Byrne, pg.110; Mac Niocaill, pg.78; Ó Cróinín (EMI), pg.50 ; Ó Cróinín (NHI), pg.216
- AU 582.1; AT 580.1
- Ó Cróinín (NHI), pg.216
- Ó Cróinín (NHI), pg.217
- AU 605.2; AT 604.3
See also 
- Annals of Ulster at  at University College Cork
- Annals of Tigernach at  at University College Cork
- Adomnán, Life of St Columba, tr. & ed. Richard Sharpe. Penguin, London, 1995. ISBN 0-14-044462-9
- Byrne, Francis John, Irish Kings and High-Kings. Batsford, London, 1973. ISBN 0-7134-5882-8
- Ó Cróinín, Dáibhí, Early Medieval Ireland: 400–1200. Longman, London, 1995. ISBN 0-582-01565-0
- Dáibhí Ó Cróinín (2005), A New History of Ireland, Volume One, Oxford: Oxford University Press
- Charles-Edwards, T. M. (2000), Early Christian Ireland, Cambridge: Cambridge University Press, ISBN 0-521-36395-0
- Gearoid Mac Niocaill (1972), Ireland before the Vikings, Dublin: Gill and Macmillan
- CELT: Corpus of Electronic Texts at University College Cork
- The Corpus of Electronic Texts includes the Annals of Ulster, Tigernach, the Four Masters and Innisfallen, the Chronicon Scotorum, the Lebor Bretnach, Genealogies, and various Saints' Lives. Most are translated into English, or translations are in progress