Papa Pius I alikuwa papa kuanzia takriban 142/146 hadi kifo chake takriban 157/161. Alitokea Aquileia, Italia na baba yake aliitwa "Rufinus".. Alimfuata Papa Hyginus akafuatwa na Papa Anicetus. Alipinga uzushi wa Gnosi na kumtenga Marcio na Kanisa. Chini yake, Yustino alifundisha katekesi mjini Roma. Tangu kale anaheshimiwa kama mtakatifu. Sikukuu yake ni tarehe 11 Julai. Watakatifu wa Agano la Kale Orodha ya Watakatifu Wakristo Orodha ya Watakatifu wa Afrika Orodha ya Watakatifu Wafransisko Orodha ya Mapapa https://www.vatican.va/content/vatican/en/holy-father.index.html#holy-father (1955) Lives of the Saints, For Every Day of the Year. New York: Catholic Book Publishing, 263.  Platina (2008). Lives of the Popes: Antiquity, Volume 1. Harvard University Press, 79. ISBN 978-0674028197.  Liber Pontificalis, Ed. Duchesne, I, 132. (2005) Dictionary of Saints, 2nd, New York: Image/Doubleday. ISBN 0-385-51520-0.  The Martyrdom of Justin. Martyrologium Romanum: ex Decreto Sacrosancti oecumenici Concilii Vaticani II instauratum auctoritate Ioannis Pauli P.P. II promulgatum, Romae 2001, ISBN 8820972107  This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913).