Diogo de Paiva de Andrada (1528–1575) was a Portuguese theologian, born at Coimbra, the son of the grand treasurer of Joao III. His original bent was towards foreign mission. He earned distinction in 1562 at the Council of Trent as the envoy of King Sebastian.
Between 1562 and 1567, Diogo de Paiva de Andradae published many controversial tracts, especially against the Lutheran, Martin Chemnitz. His first tract, De Societatis Jesu Origine, led to his being erroneously presumed a Jesuit. His De Conciliorum Auctoritate was welcomed at Rome as exalting the papal authority. Posthumous were his Defensio Tridentinae Fidei(1578) (remarkable for its learned statement of various opinions regarding the Immaculate Conception), and three sets of his sermons in Portuguese.
His nephew, Diogo, the younger (1586–1660), produced Chauleidos (1628) and other Latin poems, including sacred dramas, and a moral tract, Casamento Perfeito (1630); he also shone as an historical critic.