Yohane Kasiano (Scythia Minor, leo Dobruja, Bulgaria, 360 hivi - Marseille, Ufaransa 435 hivi) alikuwa mmonaki na mwanateolojia aliyeathiri sana Ukristo hasa kwa njia ya kitabu chake "Maongezi", anapoeleza alayofundishwa na wamonaki wa nchi mbalimbali kuhusu maisha ya kiroho. Anaheshimiwa kama mtakatifu na Kanisa Katoliki, Waorthodoksi na Waanglikana. Sikukuu yake inaadhimishwa tarehe 23 Julai au tarehe 29 Februari (tarehe 28 katika miaka mifupi). Watakatifu wa Agano la Kale Orodha ya Watakatifu Wakristo Orodha ya Watakatifu wa Afrika Orodha ya Watakatifu Wafransisko Mababu wa Kanisa Lake, Stephen. "Knowledge of the Writings of John Cassian in Early Anglo-Saxon England." Anglo-Saxon England 32 (2003): pp 27–41. Chadwick, Owen. John Cassian, Cambridge University Press, 1950. Stewart, Columba. Cassian the Monk, New York: Oxford University Press, 1998. Rousseau, Philip. "Cassian." In Simon Hornblower and Antony Spawforth, eds. The Oxford Classical Dictionary. Oxford: Oxford UP, 2003. 298. Harper, James. "John Cassian and Sulpicius Severus," Church History vol. 34 (1965):371-380. Brown, Peter.