| Rathvilly | |
| Native Name: | Ráth Bhile (Irish) |
| Settlement Type: | Barony |
| Subdivision Type: | Country |
| Subdivision Name: | Ireland |
| Subdivision Type1: | Province |
| Subdivision Name1: | Leinster |
| Subdivision Type2: | County |
| Subdivision Name2: | Carlow |
| Area Land Km2: | 181.32 |
Rathvilly is a barony in County Carlow, Ireland.
Rathvilly barony takes its name from the village of Rathvilly, which derive from the Irish language Ráth Bhile, meaning "rath of the sacred tree".
Rathvilly is found in north-east County Carlow. It contains the rivers Slaney and Derreen.
Rathvilly barony is bordered by the following baronies: to the west by Carlow; to the south by Forth; to the north by Upper Talbotstown; to the east by Ballinacor South; to the southeast by Shillelagh; and to the northwest by Kilkea and Moone.
In the 5th century, Crimthan, King of Leinster, lived at Rathvilly. The territory was that of the Uí Felmelda Tuaid, a Uí Cheinnselaig sept descended from Feidlimidh son of Enna Ceansalagh and brother of Crimthan. The MacKeoghs here were chief bards of the Kings of Leinster. An O'Neill family was cantered here.
Below is a list of settlements in Rathvilly barony: