Clarmallagh () is a barony in County Laois (formerly called Queen's County or County Leix), Ireland.
Clarmallagh means "Flat land of Maigh Locha [lake plain]", referring to Grantstown Lake.
Clarmallagh is located in south County Laois, to the south of the River Gully, and to the north of the County Kilkenny border. It contains the lower part of the Erkina River where it drains into the River Nore.
Clarmallagh barony was anciently the northernmost part of the Kingdom of Osraige (Ossory).
In the early 12th century, Finn Ua Caellaide ruled Magh Locha (Clarmallagh) separately from the rest of Ossory.
It was ruled by the àFaoláin (Phelan).
It is referred to in the topographical poem Tuilleadh feasa ar ÃÂirinn óigh (Giolla na Naomh àhUidhrÃÂn, d. 1420):
("In Magh Lacha of the warm hill slopes is ÃÂ Faolain of manly tribe; Extensive is the district due to them, which the ÃÂ Faolains have filled.")
Clarmallagh was formerly a part of the Upper Ossory barony, established by 1657; in 1842 it was divided into three cantreds: Upper Woods, Clandonagh and Clarmallagh.
Below is a list of settlements in Clarmallagh barony: