MENDES, DIOGO (b. before 1492–d.c. 1542), Marrano merchant, born in Spain, and descended from the *Benveniste family. With his brother Francisco (d. 1536), he established a business in spices and precious stones. He settled in *Antwerp, and on his brother's death was joined there by the latter's widow, later Gracia *Nasi. Mendes became a magnate in the spice trade and made large-scale loans to the governments of the Low Countries, Portugal, and England. Taking advantage of a network of factors and agents throughout Europe, he organized an "underground railway" to facilitate the flight of Marranos from Portugal, via the Low Countries (and sometimes England) to Italy and Turkey. In 1535, he and his sister-in-law, Gracia Nasi, headed the group of *New Christians who sought the help of the papal nuncio to stop the activity of the *Inquisition in Portugal. Arrested in 1532 on a charge of Judaizing, Mendes managed to exculpate himself, but after his death in Antwerp, the same charge led to the sequestration of his property.
L. Wolf, Essays in Jewish History (1934), 75–81; J. Vroman, L'Affaire Diego Mendez (1937); C. Roth, House of Nasi: Doña Gracia (1947); J.A. Goris, Les Colonies marchandes méridionales à Anvers (1925); P. Grunebaum-Ballin, Joseph Naci, duc de Naxos (1968).