Alonso de San Buenaventura (died 1594, in Belmonte, Cuenca) was a Spanish Franciscan friar and missionary evangelist.
Among these was the deacon Luis de Bolaños, later the initiator of the system of Indian reductions.
The party embarked in 1572 with the expedition led by the Adelantado Juan Ortiz de Zárate, which arrived in Asunción (the capital of present-day Paraguay) in 1575.
For many years the Franciscans worked there, spreading the Gospel and doctrine, and founding missions and reductions among the Guaraní tribes.
He stopped in Lima (present-day Peru) for two years to teach novices, and came back to Paraguay in 1588–1589 with a new group of Franciscans.