Gratian (d. before 1159) was an Italian monk and scholar known for his contributions to canon law. He became a Benedictine monk and was a lecturer at the Monastery of Saints Felix and Nabor in Bologna. During his time there, he compiled the Concordia discordantium canonum or the Decretum, a compendium that gathered together the sets of rules—or canons—for the church.  The Decretum was consulted by Church officials to ensure that they were telling members of their communities the appropriate courses of action for their transgressions.
 Peter Landau, “Gratian and the Decretum Gratiani,” in The History of Medieval Canon Law in the Classical Period, 1140-1234: From Gratian to the Decretals of Pope Gregory IX, ed. by Wilfried Hartmann and Kenneth Pennington, 22-54 (Washington D.C.: Catholic University of America Press, 2008); “Gratian: Italian Scholar,” Encyclopedia Britannica, last updated 2012, https://www.britannica.com/biography/Gratian-Italian-scholar.