Sir Thomas Molyneux (1531–1597) was a French-born statesman in Ireland during the Elizabethan era. He founded a dynasty which produced several men of distinction. His descendants became the Molyneux baronets of Castle Dillon, County Armagh.
Molyneux was born in Calais, which was the last English possession in France. His parents, of whom little is known, are thought to have died when he was very young and he was raised by John Bishin, an alderman of the town. When the French seized Calais in January 1558, he was taken prisoner, but freed after he paid a ransom of 500 crowns (the size of the ransom suggests that his family were wealthy).
He moved to Bruges and there married Catherine Stabeort (or Salaboethe), daughter of Lodowick Stabeort, a wealthy burgomaster of the town. In 1568, after the outbreak of the Dutch Revolt made life in Bruges increasingly hazardous for foreigners, Molyneux moved with his family to England, and gained the favour of Queen Elizabeth I. In 1576 he moved to Ireland.
He received a grant of land at Swords, County Dublin. He was appointed Chief Victualler to the Irish Army and Receiver of customs on the import of wine. In 1590 he was appointed Chancellor of the Exchequer of Ireland. He contributed £40 (then a very substantial sum) towards the foundation of Trinity College, Dublin.
In 1594 his qualifications to hold public office were questioned: it seems that his French birth and his years in Bruges had raised suspicions that he was a Roman Catholic, and as such ineligible for public office. At a hearing before the Court of Exchequer (Ireland), where he was examined by the Attorney General for Ireland, Sir Charles Calthorpe, he pleaded successfully that as an Englishman and a true Christian  (i.e. a Protestant), he was fit to hold any office to which the English Crown appointed him.
He and Catherine had two sons and two daughters. Samuel, the elder son, was Surveyor-General of the Queen's Works in Ireland, and sat in the Irish House of Commons as member for Mallow in the Irish Parliament of 1613-15. Daniel (1568-1632), the younger son, became Ulster King at Arms and also sat in the Irish House of Commons in 1613-15 as member for Strabane. Their daughter Catherine married Sir Robert Newcomen, the first of the Newcomen baronets, and had several children, including Sir Beverley Newcomen, 2nd Baronet, Judith, who married Arthur Ussher of Donnybrook, and Jane, who married Sir Henry Tichborne.
Through Daniel, who married Jane, daughter of Sir William Ussher of Donnybrook (father of Arthur), and had seven children, Thomas had a number of distinguished descendants, including: