ISAIA da Pisa. - Sculptor active in Rome and Naples around the middle of the 15th century. In 1447, in Rome, as successor to Filarete, he was entrusted with completing the tomb of Antonio Martinez Chiaves, cardinal of Portugal (now fragmentary in S. Giovanni in Laterano), and in the same year he took part in the work on the burial monument of Pope Eugenio IV (now in S. Salvatore in Lauro, in the cloister).
The designs for the crowning of the façade of Orvieto Cathedral date from 1450–51 (not executed). In 1456–58 he worked in Naples on the Arch of Castel Nuovo; in 1460 he was again in Rome in the service of Pope Pio II, for whom he executed the tabernacle of S. Andrea for S. Pietro, now fragmentary in the Vatican Grottoes. Among his other works are the lavabo of S. Maria Maggiore and the relief of the architrave of S. Marco. His art derives from Pisan sculpture, whose themes it continues to echo; nevertheless, his weak but clearly individual artistic personality wavers among various tendencies, ranging from love of antiquity to recollections of Donatello, producing results of vigorous plasticity and insistent calligraphic mannerism. I. da P. was the father of the sculptor Gian Cristoforo Romano.