Luchesio Modestini was a 13th-century merchant from Poggibonsi who became a foundational figure in the Franciscan Third Order. Originally a soldier and a trader known for his focus on material wealth, he underwent a spiritual conversion alongside his wife, Buonadonna de' Segni. Following the guidance of Francis of Assisi, the couple dedicated their lives to penance and charity while remaining in the world. He is recognized as a blessed within the Catholic tradition for his devotion and ascetic lifestyle.