Saint Calimerius († 280 AD) was an early bishop of Milan who is honored as a Saint in the Catholic and Eastern Orthodox churches. He was born to a noble Roman family, entered military service and reached the rank of officer when he was converted to Christianity by saints Faustinus and Jovita. He was ordained priest by Castricianus and served at the Basilica Fausta. At the death of Castricianus, he was elected bishop. When he became bishop of Milan, he preached in the region and was killed during the persecutions of Christians by Commodus, by being flung headfirst into a well. His feast day is commemorated on July 31.