Rainalducci or Rainallucci, Pietro (
pyĕ'trō rīnäldūt'chē, rīnäl-lūt'chē), d. 1333, Italian churchman (b. Corvaro, near Rieti), antipope (1328-30) with the name Nicholas V. Having separated from his wife, he became a Franciscan (1310) and was made a penitentiary in Rome. In 1328, Holy Roman Emperor
Louis IV in his struggle with Pope John XXII (at Avignon) invaded Italy and took Rome; he declared the pope deposed for heresy and set up Pietro instead. Within a year Pietro found his position untenable, and in 1330 he made submission to the pope, who pardoned him and kept him an honorable captive in the papal palace at Avignon thereafter.