Sir Thomas Smith (23 December 1513 – 12 August 1577) was an English scholar, parliamentarian and diplomat.
Born at Saffron Walden in Essex, Smith was the second son of John Smith of Walden by Agnes, daughter of John Charnock of Lancashire. He was educated at Queens' College, Cambridge, where he became a fellow in 1530, and in 1533 was appointed a public reader or professor. He lectured in the schools on natural philosophy, and on Greek in his own rooms. In 1540 Smith went abroad, and, after studying in France and Italy and taking a degree in law at the University of Padua, returned to Cambridge in 1542.
He now took the lead in the reform of the pronunciation of Greek, his views being universally adopted after considerable controversy. He and his friend, Sir John Cheke, were the great classical scholars of the time in England. In January 1543/4 he was appointed the first Regius Professor of Civil Law. He was vice-chancellor of the university the same year. In 1547 he became provost of Eton College and dean of Carlisle Cathedral.
Sir Thomas was an early convert to Protestantism, which brought him into prominence when Edward VI came to the throne being appointed Secretary of State. During the protectorate of Edward Seymour, 1st Duke of Somerset, he entered public life and was made the Secretary of State, and was sent on an important diplomatic mission to Brussels. In 1548 he was knighted. On the accession of Queen Mary I he lost all his offices, but in the reign of her sister, Elizabeth I, was prominently employed in public affairs.
He was returned as Member of Parliament for Liverpool in 1559. It became clear that he supported the religious settlement and Confessions of Westminster (1560) sitting on two committees of Inquiry. When an expert handler of the son of the King of Sweden visiting Westminster, he was sent in 1562 as ambassador to France as an emerging diplomatic talent; remaining in France from September 1562 with experienced envoy Sir Nicholas Throckmorton; and in 1572 Smith again went to France in the same capacity for a short time. However Smith came to dagger blows with Throckmorton over character and policy differences. He finally returned home in disgrace after suffering illness in April 1566.