Muskerry East (Irish: Múscraí Thoir ) is one of the baronies of Ireland, an historical geographical unit of land. Its chief town is Ballincollig. It is one of 24 baronies in the county of Cork. It may also be viewed as a half barony because some time before the 1821 census data, it was divided from its other half - Muskerry West. Other neighbouring baronies include Cork to the east (surrounding the city of Cork), Duhallow to the north (whose chief town is Newmarket) and the Barony of Barretts to the north-east .
Baronies were created after the Norman invasion of Ireland as divisions of counties and were used the administration of justice and the raising of revenue. While baronies continue to be officially defined units, they have been administratively obsolete since 1898. However, they continue to be used in land registration and in specification, such as in planning permissions. In many cases, a barony corresponds to an earlier Gaelic túath which had submitted to the Crown. This is true in the case of the Muskerry baronies whose origins go back the ancient kingdom of Múscraige - see History below.
The Múscraige and Corcu Duibne descend form Corc, a son of Cairbre Musc. While the Múscraige petty kingdoms were scattered throughout the province of Munster, the largest were centred on the present baronies of Muskerry (West and East). The tribes or septs were pre-Eóganachta, that is before the 6th century. At this time, the territory did not extend south of the River Lee (although the river bisects the current barony). A pedigree of the chieftains of the tribe may be found in the Book of Leinster. The main septs were: