Coolock (Irish: An Chúlóg) is one of the baronies of Ireland. It was constituted as part of the old county of Dublin. Today, it covers much of the northern parts of the city of Dublin and the south-eastern part of the modern county of Fingal. At the heart of the barony is the civil parish of the same name - Coolock - which is one of twenty civil parishes in the barony.
Baronies were created after the Norman invasion of Ireland as subdivisions of counties and were used for administration. While baronies continue to be officially defined units, they are no longer used for many administrative purposes. They have been administratively obsolete since 1898. Nevertheless, they continue to be used in land registration and specification such as in planning permissions. In many cases, a barony corresponds to an earlier Gaelic túath which had submitted to the Crown. However, the status of barony is still used in modern times
It is one of seven and a half baronies that used to comprise the old county of Dublin. It stretches from Dublin Airport and the Malahide estuary to the Royal Canal and River Tolka estuary (from north to south) and from the Phoenix Park to Dublin Bay (from west to east). It is located between the baronies of Nethercross (to the north), Castleknock (to the west) and Dublin City (to the south). The northern two-thirds of the barony is now administered by Fingal County Council while the southern third is subject to Dublin City Council.