Ó Callanáin, Marcas (c.1789–1846), poet, was born in Carheendiveane, Craughwell, Co. Galway. Little is known of his parents except that they were farmers and the family lived in relative comfort. According to local folklore, the Ó Callanáin family came to the area from Mayo but Antaine Raiftearaí (qv) suggests a Leinster origin in his poem ‘Fiach Mharcais Uí Challáin’. Marcas's brother Peatsaí Ó Callanáin (qv) was also a poet and the two men are often confused in folklore, known collectively as ‘Calnan’, ‘Cullán’ or ‘na Culláin’ without any differentiation between the two. Marcas Ó Callanáin's poetry and personality are regularly ascribed to Peatsaí, although they were quite the opposite of one another in both respects. This confusion may be due to the fact that Peatsaí survived Marcas by at least eighteen years and Seán Ó Ceallaigh suggests that as the memory of Marcas faded, people began to forget there were two brothers. Both were educated in a local hedge school in Tuar an Bhualadh, Carheendiveane and later worked as farmers. Marcas Ó Callanáin was also occasionally employed as a thatcher.
Ó Callanáin usually composed in the Irish language and his repertoire included humorous verses, satires and praises. Themes include marriage and the praise of women. Six of his songs are extant, two of which, ‘Mary Hynes’ and ‘Mickey Niland’ are in English. Both brothers are particularly remembered for their altercations with the blind Raiftearaí. Ó Ceallaigh suggests that the contention between Ó Callanáin and Raiftearaí may have begun by accident and that the cause was poems by both poets in praise of a local girl. Ó Callanáin's poem ‘Mary Hynes’ is said to refer to the same woman praised in Raiftearaí's ‘Máire Ní Eidhin’. According to another folklore account, it was Raiftearaí who initiated the contention by calling Ó Callanáin a thief. ‘Sciolladh Mharcais Uí Challanáin', composed by Ó Callanáin, is a biting satire on Raiftearaí and his wife Siobhán. Raiftearaí had composed ‘Ar Mharcas Ó Calláin’ and ‘Comhairle reachtabhra don chompostóir Patsaí Ó Calláin as Caithrín an Duibhéin’ prior to that and according to Ó Ceallaigh, both songs are quite insulting and crude. Ó Callanáin is termed a ‘fear fánach’ (vagrant) who made ‘caint bheag’ (small talk as opposed to composing poetry) about a ‘láí’ (spade). This is a reference to Ó Callanáin's song ‘An láí’. Peatsaí is famous for having recited the ‘sciolladh’ (scolding) in Raiftearaí's presence in a local house in 1828 and, according to tradition, made the blind poet cry. Raiftearaí is reported to have replied: ‘Ní bhfuair mise mo bhearradh gan ‘soap’ ariamh go dtí inniu’; (‘I never got my shave without soap until today’) and retorted later with the equally biting ‘Fiadhach Mharcais Uí Challáin’. Nevertheless, the contention between the Ó Callanáin brothers and Raiftearaí does not appear to have lasted long and on his death bed, the blind poet is said to have sent for Peatsaí.
Other songs composed by Ó Callanáin include ‘A, Shéain, a mhic mo chomarsan’, a song about marriage and cleamhnas (matchmaking). The song ‘Paidín Ó Catháin’, composed in 1830, is of particular interest as it is a joint composition with his brother Peatsaí. Ó Callanáin composed the first seven stanzas and Peatsaí furnished the final seven. According to Ó Ceallaigh, the song provides a valuable insight into both men's contrasting approaches to life as the difference between both sections is striking. Ó Callanáin's verses are bereft of any Christian references, while Peatsaí's are exactly the opposite.
It is not known whether Ó Callanáin ever married. He died in 1846 in the Craughwell area, aged 57 and was interred in the graveyard of Killineen, Craughwell, Co. Galway.