Caster

Gilles de Rais (ジル・ド・レェ), specifically in his Caster (キャスター) class form, is a major antagonist in Fate/Zero and a recurring character in the Fate franchise. Originally a 15th-century French nobleman and national hero who fought alongside Jeanne d’Arc, he fell into deep despair and madness following her execution. This trauma led him to abandon his faith and commit horrific atrocities, including the serial murder of children, in a twisted “scientific” attempt to provoke divine punishment and prove God’s existence.

As a Caster-class Servant, he is characterized by his tall, gaunt appearance, bulging fish-like eyes, and a “deathly pallor” that reflects his corpse-like nature. In Fate/Zero, he is summoned by Ryuunosuke Uryuu, with whom he shares a macabre bond over their mutual enjoyment of cruel and artistic murder. Despite being considered one of the weakest Servants in terms of direct combat and traditional magecraft, he is exceptionally dangerous due to his Noble Phantasm, Prelati’s Spellbook. This grimoire serves as an infinite mana source, allowing him to summon and command hordes of demonic horrors, culminating in a massive, nearly unstoppable aquatic beast. His tactical strength lies in his ability to reshape the battlefield and wage a war of attrition that few can match without overwhelming force.