Tamnyaskey (locally [ˌtamniˈaːski], from Irish Tamhnaigh Oscair 'Oscar's field (?

)'[2]) is a townland lying within the civil parish of Kilcronaghan, County Londonderry, Northern Ireland.

It lies in the west of the parish, and is bounded by the townlands of Brackaghlislea, Calmore, Granny, Mormeal, and Tullyroan.

Prior to the Plantation of Ulster, these four townlands constituted the termon (or erenagh) land of the parish, and were known as "Ballintrolla, Derreskerdan, Dirrygrinagh et Kellynahawla".

This article related to the geography of County Londonderry, Northern Ireland is a stub.