Hatto, the name of two Archbishops of Mainz. The second, and more famous, when Abbot of St. Boniface, was sent by Otho I., Holy Roman Emperor, as his ambassador to the Pope in 961, and was afterwards, as Archbishop of Mainz, one of his chief councillors. His subsequent career is legendary. Tradition said that he was punished for his oppressions by being devoured by rats in the Mausethurm, near Bingen, on the Rhine. He died about 970.