Roscommon () is a barony in County Roscommon, Ireland.
Roscommon barony is named after Roscommon town; however, it does not actually contain that town, which is located in Ballintober South.
Roscommon barony is located in the centre of County Roscommon, an area with many lakes including Lough Boderg. The only mountain is Slieve Bawn.
The Mag Oireachtaigh (Mageraghtys) were rulers here of Clann Tomaltaigh and the Muintir Roduib.
The ÃÂ FÃÂdhne (O'Feeney) were also in Roscommon barony. The O'Mulconaire were hereditary historians and bards.
The ÃÂ Maoilbhreanainn (O'Mulrenan) sept were chiefs of Clann Chonchobhair (O'Conor).
It is referred to in the topographical poem Tuilleadh feasa ar ÃÂirinn óigh (Giolla na Naomh àhUidhrÃÂn, d. 1420):
("O'Maoilbhrenainn with fame over the plain of Clann-Conchobhair, Their children are entitled to be above every tribe, that sept of the Clann-Cathail. [...] To Mac Oireachtaigh of the steeds belong Muintir Roduibh of royal judgments.")
Below is a list of settlements in Roscommon barony: