Benedictus Canonicus Sancti Petri ("Benedict, canon of St. Peter's") was a religious and liturgical writer from Rome[1] active in the first half of the 12th century.[2] Benedict was one of the four canons of the old Basilica of St. Peter, who celebrated mass in the church; almost nothing is known about his life.[2] He is the author of the Liber polypticus (or Liber Politicus),[2] which, among others, contains the Ordo Romanus; this book was written between 1140 and 1143 when he was already advanced in years.[1][2] His work is important because of the contained information about institutions and religious celebrations and feasts of 12th-century Rome.[1][2]