Martin is an extremely common name throughout the English-speaking world and, in its many variants form, throughout Europe, stemming from a diminutive of the Latin Martius, the god of war. its popularity is largely due to the widespread fame of the fourth-century saint, Martin of Tours. In Ireland, the surname may be of English,, Scottish or native Irish origin. The best-known Martins, powerful in west Galway and Galway city for centuries were of English extraction, having arrived with the Normans. They claim descent form Oliver Martin who fought in the Crusades.
The largest number of Irish origin stem from the Mac Giolla Mhairtín, "son of the follower of (St.) Martin", also anglicised as "Gilmartin", who were a branch of the O’Neills. They originally held territory in the barony of Clogher in Co. Tyrone, but were displaced westwards into the adjoining counties of Sligo and Leitrim where they are most numerous today. In Scotland, the name originated from Mac Gille Mhartainn, which was first anglicised MacMartin, and then Martin. Martins were one of the three principal branches of the Clan Cameron; there was a separate family, based in Skye, who were part of the Clan Donald.
A large majority of Martins in Ireland in 1890, almost 60%, were based in Ulster, suggesting a Scottish origin for most Irish Martins. Richard Martin ("Nimble Dick") was the source of the family fortune of the Martins of Galway. He seized vast tracts of land in west Galway from the O’Flahertys in the great land transfers of the 17th century. His great-grandson, also Richard Martin ("Humanity Dick") (1754-1834), was the most famous member of the family. He was a passionate supporter of animal welfare – hence the nickname, given him by the Prince Regent, – and was one of the founders of the Royal Society for the Prevention of Cruelty to Animals. John Martin (1812-75), born in Newry C. Down, was brother-in-law and political ally of John Mitchel, the founder of the United Irishman. He was transported to Tasmania for his political activities. On his return to Ireland he was elected a Home Rule M.P. for Meath. he was known throughout the country as "Honest John Martin".