James Cornwalsh was an Irish judge who held the office of Chief Baron of the Irish Exchequer. He was a political figure of considerable importance in fifteenth-century Ireland, and a supporter of the Lord Lieutenant of Ireland, James Butler, 4th Earl of Ormond. He was murdered as a result of a feud over the possession of Baggotrath Castle, near Dublin.

The Chief Baron of the Irish Exchequer was the Baron (judge) who presided over the Irish Court of Exchequer. This was a mirror of the equivalent court in England, and was one of the four courts which sat in the building in Dublin which is still called The Four Courts.