Manchán (d. 665) of Liath Mancháin (Lemanaghan, Co. Offaly), Irish ecclesiastic and scholar, has been given contradictory genealogies, perhaps through confusion with one of the several ecclesiastics named Manchán/ Mainchín. The most reliable source states that his father was Sillán son of Conall, descendant of Rudraige Mór of Ulster. His mother's name is given as Mella. The nature poem beginning ‘I wish, O Son of the living God . . . a hidden little hut in the wilderness’, is attributed to him, though the language is of late eighth- or early ninth-century date. According to some sources, he was one of the group of ecclesiastics who gathered together in 664 to pray and fast to God for a plague that would reduce Ireland's teeming ‘lower orders’. The plague duly came and killed a great many, together with those who had prayed for its arrival, including Manchán. A reliquary associated with Manchán is preserved locally at Boher church. His death is noted in most of the annals; he is commemorated in the Irish martyrologies on 20 January.
Another notable ecclesiastic of the same name was the scholar Manchán (Manchianus, Manchéne) , abbot of Min Droichit (barony of Upper Ossory, Co. Offaly), who was also associated with Disert Gallen, Co. Laois. He is most likely the Manchianus referred to as pater and sapiens by the Irish Pseudo-Augustine (Augustinus (Pseudo-) (qv)) in the preface to ‘De mirabilibus sacrae Scripturae’; since the work is internally datable to 655 this identification is plausible. Possibly the same scholar is also named in the anonymous Irish commentary on the ‘Catholic Epistles’ as ‘M., doctor noster’, and cited with reference to an exegesis of the epistle of James. This commentary survives in a single manuscript in Karlsruhe and is remarkable for adverting to the opinions of several seventh-century Irish scholars, including Lathcen (qv), Breccanus, Banbán and Bercanus son of Áed. The death of Manchán of Min Droichit is recorded in a number of the annals at 652, and he is commemorated in the Irish martyrologies on 2 January; St Mainchín (qv) of Limerick has the same feast-day, which suggests that the two are duplicates.