Castleknock (Irish: Caisleán Cnucha) is a civil parish and a townland located in the south-western corner of the modern county of Fingal, Ireland.
In geology, the parish rests on a substratum of limestone and comprises 2943 statute acres, the whole of which is arable land.
In 1773, an Act of the Privy Council united the parish with the curacies of Clonsilla and Mulhuddart.
The living (of the ecclesiastical parish) was a vicarage in the Diocese of Dublin which was: "... endowed with a portion of the great tithes, and united to the prebend of Castleknock and the rectory of Clonsillagh and curacy of Mullahidart, with cure of souls: it is in the patronage of the Bishop.
To the west, it is bounded by the civil parish of Clonsilla which is the location of Blanchardstown Shopping Centre.
To the east lies the 8th lock of the Royal Canal in the townland of Pelletstown and the Cabra Gate of the Phoenix Park.
Populated places in the civil parish include: Blanchardstown, Castleknock, Ashtown, Cabra, Corduff, Laurel Lodge.
For convenience, the table groups the townlands by their location in one of the modern local authority areas.