Sir Thomas Elyot (c. 1490 – 26 March 1546) was an English diplomat and scholar.
Thomas was the child of Sir Richard Elyot's first marriage with Alice De la Mare, but neither the date nor place of his birth is accurately known. Anthony Wood claimed him as an alumnus of St Mary Hall, Oxford, while C. H. Cooper in the Athenae Cantabrigienses put in a claim for Jesus College, Cambridge. Elyot himself says in the preface to his Dictionary that he was educated under the paternal roof, and was from the age of twelve his own tutor. He supplies, in the introduction to his Castell of Helth, a list of the authors he had read in philosophy and medicine, adding that a "worshipful physician" (Thomas Linacre) read to him from Galen and some other authors.
In 1511 he accompanied his father on the western circuit as clerk to the assize, and he held this position until 1528. In addition to his father's lands in Wiltshire and Oxfordshire he inherited in 1523 the Cambridge estates of his cousin, Thomas Fynderne. His title was disputed, but Cardinal Wolsey decided in his favour, and also made him clerk of the Privy Council. Elyot, in a letter addressed to Thomas Cromwell, says that he never received the emoluments of this office, while the empty honour of knighthood conferred on him when he was displaced in 1530 merely put him to further expense. In that year he sat on the commission appointed to inquire into the Cambridgeshire estates of his former patron, Wolsey. He was appointed High Sheriff of Oxfordshire and Berkshire in 1527.