Nicholas Barnewall may refer to:
Nicholas Barnewall (Irish judge) (died after 1465), Lord Chief Justice of Ireland Nicholas Barnewall, 1st Viscount Barnewall (1592–1663), Irish landowner and politician Nicholas Barnewall, 3rd Viscount Barnewall (1668–1725), Irish nobleman Nicholas Barnewall, 14th Baron Trimlestown (1726–1813), Irish landowner