Tinnakill Castle, Tower house ruin in County Laois, Ireland

Tinnakill Castle is a ruined four-story limestone tower house located in the parish of Coolbanagher in Portnahinch Barony. The structure measures approximately 10 by 11.8 meters and displays the typical features of a medieval tower dwelling.

Some sources hold that Eoin Carragh MacDonnell, called John the Scabbed, built the four-storey tower in the mid-15th century on the site of an earlier castle; others date it to the 16th century and note it may first have belonged to the O'Connor family before passing to the MacDonnells. The last MacDonnell holder, James McDonnell, lost the site after the Irish Rebellion of 1641, and the tower later fell into ruin, with structural works to protect it in the 19th century.

The name comes from Irish 'Tigh na Coille', meaning House of the Wood. A carved sheela na gig figure once decorated the second floor, a symbolic form of representation found in medieval Irish buildings.

The ruins are located in County Laois and accessible alongside many other medieval structures in the area. Visitors should expect uneven ground and possibly limited access due to the age of the remains.

A sheela na gig was carved on a limestone window jamb on the second floor; it was removed in later centuries, so visitors today see only the opening where the figure once sat. The tower measures up to 10 by 11.8 metres.