(Note: all infos are taken from Wikipedia)
Fate/zero (フェイト/ゼロ Feito/zero) is a prequel to Type-Moon's visual novel Fate/stay night. Fate/zero takes place 10 years prior to the events of Fate/stay night, detailing the events of the 4th Holy Grail War in Fuyuki City. The War of the Holy Grail is a contest in which seven magi summon seven Heroic Spirits to compete to obtain the power of the "Holy Grail," which grants a miracle. After three inconclusive wars for the elusive Holy Grail, the Fourth War commences.
Fate/zero (フェイト/ゼロ Feito/zero) is a prequel to Type-Moon's visual novel Fate/stay night. Fate/zero takes place 10 years prior to the events of Fate/stay night, detailing the events of the 4th Holy Grail War in Fuyuki City. The War of the Holy Grail is a contest in which seven magi summon seven Heroic Spirits to compete to obtain the power of the "Holy Grail," which grants a miracle. After three inconclusive wars for the elusive Holy Grail, the Fourth War commences.
Kiritsugu Emiya (衛宮 切嗣 Emiya Kiritsugu)
- Master of Saber, unconfident and unhappy, adopts a strategy of exploiting a magus' weak point using technology. A coldblooded assassin skilled in hunting magicians. Entered the Einzbern family to realize his lifelong wish: to obtain the Holy Grail.
- Kirei Kotomine (言峰 綺礼 Kotomine Kirei)
- Master of Assassin, works for Tokiomi and does everything he is asked to do to the best of his ability, but lacks fulfillment, which he sees mirrored in Kiritsugu, for whom he feels a compulsive hatred.
- Irisviel von Einzbern (アイリスフィール・フォン・アインツベルン Airisufīru fon Aintsuberun)
- Heroine of the story, the mother of Illyasviel von Einzbern and Kiritsugu's wife. A homunculus prototype created by the Einzbern family with the idea to give birth to an ultimate homunculus. Like many of the Einzberns, she is skilled in alchemy. Irisviel serves as Saber's proxy Master, since Kiritsugu believes that he and Saber are incompatible.
- Tokiomi Tōsaka (遠坂 時臣 Tōsaka Tokiomi)
- Father of Rin Tōsaka and Sakura Matō, Master of Archer, arrogant and manipulative, arranges for Kirei Kotomine to be his "pupil". Thinks highly of Kotomine and has him serve him.
- Aoi Tōsaka (遠坂 葵 Tōsaka Aoi)
- Mother of Rin Tōsaka and Sakura Matō. Childhood friend of Kariya Matō. Though she is devastated by Tokiomi's decision to adopt away Sakura, she quietly accepts the decision as the wife of a mage.
- Waver Velvet (ウェイバー・ベルベット Ueiba Berubetto)
- Master of Rider, future Lord El-Melloi II. Steals his teacher's artifact and uses it to summon Rider. Plans to use the Grail to force the Magus Association to recognize his genius. Despite his difficulties with Rider's overbearing nature, Waver and his Servant form a strong relationship.
- Maiya Hisau (久宇 舞弥 Hisau Maiya)
- Assistant to Kiritsugu Emiya. She is cold and professional, which makes it easier for Kiritsugu to act as he needs to.
- Kariya Matō (間桐 雁夜 Matō Kariya)
- Uncle of Shinji Matō, Master of Berserker, makes a deal with Zōken Matō that he will win the Grail War in exchange for Sakura Tōsaka's freedom. He is the only member of Matō family who truly loves Sakura, and is upset that Tokiomi allowed his younger daughter to be adopted by Zōken. However, the war is taxing on Kariya, not only because of his lack of formal training, but also due to the nature of the Matō family's magecraft and the demands required to maintain Berserker.
- Ryūnosuke Uryū (雨生 龍之介 Uryū Ryūnosuke)
- Master of Caster, sociopathic serial killer who summons Caster after murdering a family and using their blood as a component in the summoning ritual. He does not seek the Holy Grail, but follows Caster in order to find new thrilling ways to kill people and relieve his boredom.
- Kayneth Archibald El-Melloi (ケイネス・エルメロイ・アーチボルト Keinesu Erumeroi Achiboruto)
- Master of Lancer, a nobleman from the Magus Association and genius magus. His artifact is stolen by Waver Velvet, but he manages to summon Lancer anyway. While he holds the command spells for Lancer, the energy to materialize the Servant is maintained by Sola-Ui. He is confident in his abilities and takes pride in his heritage, but finds the extent of Kiritsugu's untraditional and underhanded tactics both offensive and unexpectedly challenging to overcome.
- Risei Kotomine (言峰 璃正 Kotomine Risei)
- Kirei Kotomine's 80 year old father, a priest in the Church, the regulator of the 4th Holy Grail War. He is a friend of Tokiomi Tōsaka and actively supports him. While he is proud of his son, who has demonstrated himself to be a perfect heir, Risei fails to understand Kirei in any sense.
- Sola-Ui Nuada-Re Sophia-Ri (ソラウ・ヌァザレ・ソフィアリ Sorau Nuazare Sofiari)
- The daughter of the head of the spiritual evocation division. She is engaged to Kayneth as a result of a strategic marriage arrangement and the decision of her family to entrust their crest to her brother instead. However, she is coldhearted and does not reciprocate Kayneth's love for her; instead, she becomes infatuated with Lancer, who in turn does not reciprocate her feelings and regards her only as his Master's wife.
Servants participating in the Fourth Holy Grail War and their true identities:
- Saber (セイバー Seibā, Arturia Pendragon (アルトリア Arutoria))
- The same character from Fate/stay night. Known as the King of Knights, she maintains a high code of honour. Though she and Kiritsugu are Servant and Master seeking the same ultimate goal of peace, their differing ideological perspectives result in a strained relationship where Kiritsugu does not directly acknowledge Saber.
- Archer (アーチャー Āchā, Gilgamesh (ギルガメッシュ Girugamesshu))
- A rogue servant in Fate/stay night, the King of Heroes. He dislikes the presence of Saber and Rider in particular since they were kings like he was. Much to Tokiomi's displeasure, Gilgamesh has difficulty acting covertly or regaining his temper when his considerable pride is wounded.
- Lancer (ランサー Ransā, Diarmuid Ua Duibhne (ディルムッド・オディナ Diarumuddo Odina))
- A Servant with two Noble Phantasms: Gae Buidhe - Golden Rose of Mortality and Gae Dearg - Crimson Rose of Exorcism, which can counter Saber and Berserker's abilities. As a knight, he holds a strong sense of honour in battle and loyalty to his master.
- Rider (ライダー Raidā, Iskander (イスカンダル Isukandaru))
- The King of Conquerors, who desires to defeat Saber in particular because he believes her ideal regarding kingship are deluded and that she would thrive as one of his followers. Has several Noble Phantasms, the first of which is Gordius Wheel - Wheel of Heaven's Authority, which summons an ox-drawn chariot when Iskander slices the air with his sword. His eccentric and overbearing personality along with his incredible abilities creates difficulties for his Master and their opponents.
- Caster (キャスター Kyasutā, Gilles de Rais (ジル・ド・レェ Jiru Do Rē))
- A Servant who derives pleasure from first providing his victims a moment of relief before terrorizing them and then killing them. Expresses an interest in Saber because he has mistaken her for Jeanne d'Arc, with whom Bluebeard has an infatuation.
- Berserker (バーサーカー Bāsākā, Lancelot of the Lake (サー・ランスロット Sā Ransurotto), previously known as the Black Knight)
- A Servant who possesses the ability to use practically any object as a Noble Phantasm, allowing him to match Gilgamesh in combat. His madness has reduced him to a mindless, though dangerously skilled, fighter. Despite his insanity, he is still able to instinctively recognize Saber.
- Assassin (アサシン Asashin, Hassan-i Sabbah (ハサン・サッバーハ Hasan Sabbāha))
- Assassin is actually composed of several entities rather than just one. They act as reconnaissance agents for Tokiomi and Kirei after Gilgamesh "kills" one of them.
