Laichtín (d. 622) son of Toirbín, abbot of Achad Úr (Freshford, Co. Kilkenny), is a shadowy figure reputed to have been born in the sixth century. Pádraig Ó Riain has argued that he was a Christianised version of the Celtic divinity Lug, whose festival, Lugnasa, was celebrated on 1 August. Tradition claims that Laichtín's father was Tarbén son of Nuachar, descendant of Cairpre Músc, that he belonged to the Uí Chainnig branch of the Múscraige, and was born in a place called Belach Febrat (Ballyhoura Hills, Co. Cork); his placement in this locale may have been due to the confusing of Laichtín with St Molaga (qv) of Templemolaga, also probably a representation of Lug. At the age of 15 he went to the monastic school of Bangor, Co. Down, which had recently been founded by Comgall (qv), where he was placed in the care of Molua, later abbot of Clonfertmulloe and, according to Ó Riain, also a version of Lug. After completing his training, Laichtín established a monastic foundation at Achad Úr, on the borders of the ancient kingdom of Osraige (Ossory). He later established foundations at Domnach Mór Mittíne (Donoughmore, Co. Cork) and at Lis Lachtín (Lislaughtin, Co. Kerry). The remains of the doorway of a Romanesque church still stand at Freshford; a nearby well said to have been dedicated to the saint cannot now be located.
Many miracles are ascribed to Laichtín; some are associated with his arm, the arm being a notable feature of the divinity Lug. Laichtín's arm was preserved in a reliquary shrine made for it by the kings of Munster c.1118/21. The relic was preserved at Kilnamona, Co. Clare, and later at Lislaughtin. In the eighteenth century Jonathan Swift (qv) took it to England, where it was preserved by the Fountaine family at Narford Hall, Swaffham, Norfolk. The shrine was purchased by the Royal Irish Academy in 1884, and is now in the National Museum of Ireland.
Laichtín is said to have died on 19 March 622. He is commemorated on 19 March in all of the Irish and some foreign martyrologies, where he is sometimes styled ‘bishop’. Traditions of the saint are related in the Life (§47) of Carthach (qv) and the Life (§10) of Mochóemóc (qv), but they have no historical validity.