Gerardo Sasso, also known as Blessed Gérard, was an Italian lay brother in the Benedictine Order in the Catholic Church who was appointed as rector of the hospice in Jerusalem at Muristan in 1080. In the wake of the success of the First Crusade in 1099, he became the founder of the Order of St John of Jerusalem, also known as the Knights Hospitaller, an organization that received papal recognition in 1113. As such, he was the first Grand Master of the Knights Hospitaller.