This name is derived from a diminutive of Nicholas. The Gaelic version of the name of Ó Coileáin, which means a young dog. Until the 13th century, the clan were lords of the barony of Connello in Co. Limerick and today the name remains common in both Co. Limerick and Co. Cork.

Two place-names in Ireland derive their name from Collins: Collinstown is the site of Dublin airport and for many years the airport was referred to simply as Collinstown; in Co. Westmeath, Collinstown is a small crossroads village not far from Lough Lene.

The most famous holder of the name was Michael Collins (1890-1922), born at Woodfield, near Clonakilty, Co. Cork. He was closely involved in the War of Independence, where many of his exploits were legendary, and then in the Anglo-Irish negotiations that resulted in the 1921 treaty. He was killed at Béal na mBáth in west Cork in 1922. This site, and also his birthplace, are preserved.