Francis Mathew, 1st Earl Landaff (September 1738 – 30 July 1806) was an Anglo-Irish politician and peer.
Mathew was the only son and heir of Thomas and Mary Mathew. His father's family had settled in Ireland from Wales a generation before. Mathew served in the Irish House of Commons as the Member of Parliament for Tipperary between 1768 and 1783. In 1769 he was High Sheriff of Tipperary. On 12 October 1783 he was raised to the Peerage of Ireland as Baron Landaff, of Thomastown in the County of Tipperary, and assumed his seat in the Irish House of Lords. On 4 December 1793 he was further honoured when he was made Viscount Landaff.
From 1794 to 1797, Lord Landaff was Colonel of the 14th Regiment of Foot. On 22 November 1797 he was made Earl Landaff. Following the implementation of the Acts of Union 1800, he was elected as one of the 28 original Irish representative peers and took his seat in the British House of Lords. Between 1769 and his death he also held the position of Custos Rotulorum of Tipperary.
Lord Landaff married three times. He was succeeded in his titles by his eldest son from his first marriage, Francis Mathew. Another son was the politician, Montague James Mathew.