Oliver Plunkett (kwa Kieire: Oilibhéar Pluincéid; Loughcrew, County Meath, Ireland, 1 Novemba 1625 – Tyburn, London, Uingereza, 1 Julai 1681) alikuwa askofu mkuu wa Armagh, kaskazini mwa Ireland, kuanzia mwaka 1670. Baada ya njama ya Kipapa aliendelea, ingawa kwa siri, kutokana na dhuluma ya serikali. Hatimaye alikamatwa na kuhukumiwa adhabu ya kifo kwa kueneza imani Katoliki. Hivyo alinyongwa na kuraruliwa Papa Pius XI alimtangaza mwenye heri tarehe 23 Mei 1920, halafu Papa Paulo VI tarehe 12 Oktoba 1975 alimtangaza kuwa mtakatifu mfiadini. Sikukuu yake ni tarehe ya kifodini chake. Watakatifu wa Agano la Kale Orodha ya Watakatifu Wakristo Orodha ya Watakatifu wa Afrika Orodha ya Watakatifu Wafransisko Earlier biographers gave his date of birth as 1 November four years later, but since the discovery of an ancient reference to Oliver Plunkett’s birth in the Bodleian Library, Ashmolean, MS.436 which stated: "He was born on 1st. November 1625" biographers of Plunkett since the 1930s agree on 1625.