Seamus Mac Cruitín (1815-1 September 1870), was a 19th-century Irish poet and bard.
Mac Cruitín was a native of County Clare, apparently the area of Ennistymon. He was a member of the same family as Aindrias Mac Cruitín and Aodh Buí Mac Cruitín. Seamus claimed he was sixth in line of descent from Sean, a brother of Aindrias. He is thought to have been the product of an irregular union between a Tadhg Mac Mac Cruitín and an unknown woman. The names of his siblings, if he had any, are unknown.
Associates included the scribe Michael O Raghallaigh; Brian O Luanaigh (1828–1901), later Professor of Irish at the Catholic University of Irish; John MacHale, Archbishop of Tuam; Eugene O'Curry; William Smith O'Brien.
Mac Cruitín had spent some time in County Kerry, and by his early 20s was working as a schoolmaster. His works included translations of Brian Merriman's The Midnight Court, collected songs and poems for Eugene O'Curry, translations and versions for O'Brien, in addition to composing original material.
After years of heavy drinking and bad health, Mac Cruitín's health broke down. He developed a severe illness which developed into rheumatic fever. He was brought to Ennistymon Workhouse, where he died on 1 September 1870. Mac Cruitín was buried in an unmarked grave in the paupers' plot of Ennistymon Workhouse. His death was not reported in the local papers. The official cause of death was cirrhosis of the liver.