Thomas Shelton (fl. 1604–1620) was a translator of Don Quixote. Shelton's translation of the first part of the novel into English was published in London in 1612. It was the first translation into any language.
Shelton was a Roman Catholic from Dublin. He may have been educated in Spain, where a 'Thomas Shelton, Dublinensis' was listed as a student in Salamanca.
Shelton's activities in Ireland brought him to the attention of the English intelligence service. He seems to have been employed in carrying letters to persons in England from Lord Deputy Fitzwilliam at Dublin Castle. However, evidence emerged that he was hostile to the English crown: a letter was intercepted in which he offered his services to Florence MacCarthy, who was seeking to arrange a military intervention by the king of Spain. (The Spanish sent an expedition to Kinsale, Ireland in 1601).
In 1600 a spy reported that Shelton and one Richard Nugent were at the headquarters of the Irish rebel Tyrone. Shelton and Nugent were reported to be planning to travel to Scotland, but they changed their destination to Spain. Whether they arrived in Spain is not clear as they both ended up in Flanders. Nugent was to claim he left Ireland because he was neglected in love, publishing Cynthia, containing direfull sonnets, madrigalls and passionate intercourses, describing his repudiate affections expressed in loves owne language.
Shelton's dedication of his major literary work to Theophilus Howard has led to speculation as to the connection between them. The Oxford Dictionary of National Biography suggests they could have met in the Low Countries in 1610. Another suggestion is that the connection was via Lady Suffolk, Theophilus' mother. According to Alexander T. Wright, in a paper published in October 1898, Lady Suffolk had three relatives bearing the name Thomas Shelton, and the author may therefore have been related. Moreover, Lady Suffolk received money from the King of Spain on the recommendation of the Spanish ambassador. She was of interest to the Spanish because of her perceived influence on the Earl of Salisbury.