Antonio Grassi was a 17th-century Italian priest belonging to the Oratory of Saint Philip Neri. Born Vincenzo Grassi in Fermo, he joined the Oratorians in 1609 and was ordained in 1617. He was recognized for his deep piety, his extensive knowledge of sacred scripture, and his commitment to the teachings of Saint Philip Neri. Throughout his ministry in Fermo, he served as a dedicated confessor, a counselor, and a mediator between local factions, while also dedicating himself to charitable works and the spiritual education of children.