The County of Coleraine, also known as County Coleraine, was a county of Ireland. It was the only one of the original 32 counties of Ireland to be abolished before the twentieth century.

It was created between the rivers Bann and Foyle in 1585 by John Perrot during the reign of Elizabeth I of England, with the intention of administering it from Coleraine, but in fact its courthouse and jail were built at Desertmartin . Beyond this, English control of the territory was nominal, so in 1607 almost the entire county was confiscated from its Irish owners, and in 1609, it was given to the Corporation of London and its livery companies, who were commanded to undertake its plantation.

The area to be planted included the entirety of County Coleraine, a barony of northern County Tyrone, the environs of Coleraine in County Antrim and a small area of County Donegal around Lough Foyle. In 1613, this larger area was incorporated into the new County Londonderry, with its county town in new walled city of Londonderry on the west bank of the Foyle, opposite the destroyed town of Derry.