(b. ca. 1430, Saint-Pol-de-Léon, d. 1496, Toledo)
French architect and possibly sculptor, active in Spain. He was the most prominent exponent of the Hispano-Flemish or Isabelline style. Guas was the son of the mason Pedro Guas, who arrived in Toledo from Brittany c. 1440 with the group of masons led by Hanequin de Bruselas, in whose workshop Juan Guas probably trained. The first proof of his works dates back to 1448, year in which he collaborated with his father (possibly as a sculptor) on works done at the Puerta de los Leones (Lions' Gate) on the Cathedral in Toledo. His supposed brothers Enrique and Bonifacio, cited as assistants through the mistaken interpretation of an inscription and a document, never existed. In 1453 he was named as an assistant in the building of the Puerta de los Leones. In 1458 he was listed as a master mason in the cathedral accounts, and in the following year he married Marina Álvarez.
His notable buildings are: the Monasterio de San Juan de los Reyes, Toledo (between 1479 and 1480 for Ferdinand and Isabella), the Infantado Palace (Palacio del Infantado), Guadalajara (for the powerful Mendoza family), and the Segovia Cathedral (serving as Master of Works between 1473 and 1491).
With Guas's talent for fusing Gothic and Mudéjar forms typical of Castilian culture, his architecture is considered some of the most interesting architecture of late medieval Spain.