Alonso Antonio de San Martín

Alonso Antonio de San Martín (1642 – 5 July 1705) was a Roman Catholic prelate who served as Bishop of Cuenca (1681–1705) and Bishop of Oviedo (1675–1681).

Alonso Antonio de San Martín was born in Madrid, Spain in 1642. On 1 October 1675, he was selected by the King of Spain and confirmed by Pope Clement X on 16 December 1675 as Bishop of Oviedo. In April 1676, he was consecrated bishop by Francisco de Rois y Mendoza, Archbishop of Granada, with Clemente Alvarez López, Bishop of Guadix, and Melchior de Escuda Aybar, Titular Bishop of Utica, serving as co-consecrators. On 21 October 1681, he was appointed during the papacy of Pope Innocent XI as Bishop of Cuenca.

He served as Bishop of Cuenca until his death on 5 July 1705.