Ruler (ルーラー, Rūrā?), the Standard-Bearer who Correctly Guides the Holy Grail War (聖杯戦争を正しく導く旗手, Seihai Sensō wo Tadashiku Michibiku Kishu?), is the Ruler-class Servant in the Great Holy Grail War of Fate/Apocrypha. She is one of the Servants of the Protagonist of the Grand Order conflicts of Fate/Grand Order.