Sylvester of Assisi (died 1240) was born in Assisi in the second half of the 12th century. He was the son of Rosone di Monaldo, who was the brother of Favarone di Monaldo, the father of St. Clare of Assisi.
Sylvester was ordained a diocesan priest and became a canon of the cathedral church of San Rufino in Assisi. In 1209 he joined Saint Francis of Assisi, and became the first priest in the primitive fraternity. He was known in the order for his strict observance of the life of poverty and contemplation. Together with St. Clare he prayed for enlightenment to discern the will of God for St. Francis. He often accompanied Francis during his preaching tours. Once, in the village of Arezzo, it was claimed by the residents that Sylvester's preaching and prayers brought peace to the city, which was falling prey to hatred and violence amongst its citizens.
St. Bonaventure, in a special way, mentions the visions which Sylvester had concerning st. Francis. Sylvester died in Assisi in 1240. Sylvester is one of the four companions who are buried near the tomb of St. Francis in the Basilica of St. Francis in Assisi.
2 Cel 109; LegMaj III,5
Walsh, Michael. A New Dictionary of Saints (Liturgical Press, 2007) p. 567