Hatto II

Hatto II (died 18 January 970) was the archbishop of Mainz from 968 to 970.
While in office, he built the church of St George on the island of Reichenau, donated heavily to the abbeys of Fulda and Reichenau, and was a patron of the chronicler Regino of Prüm.
A well known folk tale describes Hatto as a cruel and oppressive ruler, who was finally punished in being eaten alive by mice - an event which supposedly happened in the Mouse Tower (see details on that page). There is, however, no indication of the tale being historically true, and similar tales were attached to various other rulers as well.
The story's reference to Hatto's demand for tribute or a toll ("Maut" in German) of passing ships from the tower, as well as its later use as a customs collection tower, provide a suggested etymological origin for its name, with "Mautturm" (toll tower) eventually becoming "Mäuseturm".