Dillon (De Leon), Thomas (1613–90), Jesuit and scholar, was born in Ireland and educated in Spain. In 1627 he entered the Society of Jesus in Seville. He taught philosophy and then scholastic and moral theology at the society's colleges at Seville and Granada. In 1640 he was professor of humanities at Cadiz and, in 1661, he was deputed by the province of Andalusia to the eleventh general congregation. He was highly regarded for his knowledge of languages, including Greek, Hebrew, and Arabic. He produced two major works; the first, entitled ‘Lección sacra en la fiesta célebre que hizo el collegio de la Compagnia de Jesús de la ciudad de Cadiz en hazimiento de gracias a Dios Neustro Señor por el complimiento del primer siglo de su sagrada religión’, was published on the centenary of the Society of Jesus in 1640. His second work was a manuscript commentary on the book of Maccabees. By 1676, Dillon, or de Leon as he was also known, was residing at the Jesuit college in Granada suffering from ill health and failing eyesight. He died 7 February 1690 at Granada.
G. Oliver, Collections towards illustrating the biography of the Scotch, English and Irish members of the Society of Jesus (1838), 225; E. Hogan, ‘Chronological catalogue of the Irish members of the Society of Jesus, from the year 1550 to 1814’, Records of the English province of the Society of Jesus, ed. H. Foley, vii, no. 2 (1883), 1–96; DNB, v, 992; Crone, 53; ODNB