Atto of Pistoia

Saint Atto (1070 – 22 May 1153) was a Portuguese Roman Catholic bishop and a professed member from the Vallumbrosan Order as well as the Bishop of Pistoia and a noted historiographer.

He was born at Beja in the Portuguese region of Alentejo in 1070. He became Abbot of Vallombrosa (in Tuscany) in 1105, and in 1135 was made Bishop of Pistoia, also in Tuscany. He wrote lives of St. John Gualbert and St. Bernard of Vallombrosa, bishop of Parma. In 1145 he transferred to Pistoia certain relics of the Apostle St. James of Compostella. His correspondence on that occasion is found in Ferdinando Ughelli, Italia sacra, VII, 296.