原作は虚淵玄の同名伝奇ライトノベルで、キャラクター原案は武内崇。ビジュアルノベル『Fate/stay night』の10年前の世界を描いたスピンオフ作品。魔術師たちが聖杯をめぐる様々な戦いを繰り広げてゆく。
聖杯戦争―奇跡を叶えるという『聖杯』をめぐり、魔術師（マスター）7人は英霊（サーヴァント）と契約、最後の一人に残るべくこの未知なる究極の闘いに挑むことに。4度目の闘いが始動、勝利を手にするため魔術師たちは戦場へ向かうが、ただ一人、言峰綺礼は闘いの意義を摸索していた…。令呪が如何に自分に与えられたのか綺礼は煩悶する。やがて綺礼は宿命のライバルに出会う。衛宮切嗣―彼もまた苛烈に聖杯を追い求めていた。
With the promise of granting any wish, the omnipotent Holy Grail triggered three wars in the past, each too cruel and fierce to leave a victor. In spite of that, the wealthy Einzbern family is confident that the Fourth Holy Grail War will be different; namely, with a vessel of the Holy Grail now in their grasp. Solely for this reason, the much hated "Magus Killer" Kiritsugu Emiya is hired by the Einzberns, with marriage to their only daughter Irisviel as binding contract.
Kiritsugu now stands at the center of a cutthroat game of survival, facing off against six other participants, each armed with an ancient familiar, and fueled by unique desires and ideals. Accompanied by his own familiar, Saber, the notorious mercenary soon finds his greatest opponent in Kirei Kotomine, a priest who seeks salvation from the emptiness within himself in pursuit of Kiritsugu.
Based on the light novel written by Gen Urobuchi, Fate/Zero depicts the events of the Fourth Holy Grail War—10 years prior to Fate/stay night. Witness a battle royale in which no one is guaranteed to survive.
