Ballaghaderreen is a town in County Roscommon, Ireland. It was part of County Mayo prior to 1898. It is in the north-west of the county, near the borders with counties Mayo and Sligo, just off the N5 road. The population was 1,808 in the 2016 census.

The Bishop of Achonry is an episcopal title which takes its name after the village of Achonry in County Sligo, Ireland. In the Roman Catholic Church it remains as a separate title, but in the Church of Ireland it has been united with other bishoprics.