Italian humanist and Classical scholar, one of the pioneers of Greek studies in Renaissance western Europe and foremost teacher of humanistic scholars.

Following studies in Italy and the establishment of his first school in Verona in the 1390s, Guarino studied at Constantinople (1403–08), where he was a pupil of Manuel Chrysoloras (Chrysoloras, Manuel). Returning to Italy with a valuable collection of Greek manuscripts, he taught Greek at Florence (1410) and Venice (1414) and compiled Regulae grammaticales (1418), the first Renaissance Latin grammar. It appeared in numerous editions and was used well into the 17th century. After two terms as master of rhetoric in Verona, Guarino became tutor to Leonello, son of Nicolò d'Este, lord of Ferrara (Este, House of), in 1430. Guarino prepared new editions of various Latin authors and translated works of Strabo and Plutarch. His linguistic talents were employed by Greek and Latin churchmen at the Council of Ferrara-Florence (Ferrara-Florence, Council of) (1438–45). With his colleague Gasparino da Barzizza (Barzizza, Gasparino da) and former pupil Vittorino da Feltre, Guarino helped set the pattern for studies in humanism.