Papa Yohane XXI (1215 – 20 Mei 1277) alikuwa Papa kuanzia tarehe 13 Septemba 1276 hadi kifo chake. Alitokea Lisbon, Ureno. Jina lake la kuzaliwa lilikuwa Pedro Julião au Pedro Hispano. Alimfuata Papa Adriano V akafuatwa na Papa Nikolasi III. Orodha ya Mapapa https://www.vatican.va/content/vatican/en/holy-father.index.html#holy-father https://www.vatican.va/content/vatican/en/holy-father.index.html#holy-father Maxwell-Stuart, P. G. Chronicle of the Popes: The Reign-by-Reign Record of the Papacy from St. Peter to the Present, Thames & Hudson, 2002, p. 119. ISBN 0-500-01798-0. Wikimedia Commons ina media kuhusu: John XXI Kuhusu Papa Yohane XXI katika Kamusi Elezo ya Kikatoliki