Sir Cahir Rua O'Doherty (ama; 1587<unk>5 Luulyo 1608) wuxuu ahaa Madaxii ugu dambeeyay ee Gaelic ee Magaca Clan O'Doherty iyo Lord of Inishowen, oo hadda ah Degmada Donegal. O'Doherty wuxuu ahaa nin daacad ah oo caan ah intii lagu jiray kacdoonka Tyrone waxaana loo yaqaanay Boqoradda O'Doherty adeeggiisa Boqortooyada intii lagu jiray dagaalka. Dagaalkii ka dib O'Doherty wuxuu damacsanaa inuu noqdo maxkamad waxaana uu dalbaday boos ka mid ah gurigii Henry Frederick, Amiirka Wales, laakiin wuxuu si isa soo taraysa u khilaafay mas'uuliyiin Irish ah sida Viceroy Sir Arthur Chichester iyo Guddoomiyaha Derry Sir George Paulet. Sanadkii 1608 wuxuu bilaabay kacdoonkii O'Doherty, isagoo Derry ka qabsaday Paulet wuxuuna ku gubay dhulka
Waxaad O'Doherty waxaa markii dambe lagu dilay dagaal ka dhacay Kilmacrennan, kacdoonka ayaa si deg deg ah u burburay.