John of the Grating was a 12th-century Cistercian prelate who served as the Bishop of Aleth. Born in Brittany in 1098, he was appointed to his episcopal position in 1144. To safeguard his diocese from pirate attacks, he successfully moved the episcopal see to Saint-Malo in 1146 with the approval of Pope Eugene III. His nickname, which refers to a protective shrine grating, became associated with his identity as a defender of the faith and his administrative duties.