Piyu XI, Piyu Tunka Mayani, Achille Damiano Ambrogio Ratti  (latin aru: Pius PP. XI, Italya aru: Papa Pio XI, Kastilla aru: Papa Pío XI, (* Desio, 1857 mara 31 uru Llamayu phaxsin yuritayna - † Roma, 1939 mara 10 uru Anata phaxsin yuriwi)  jacha marka jaqi, Awki Papa (1922-1939).