**Leonidas I** manifests as a Lancer-class Servant, his legend forged in ancient Sparta and eternally defined by the Battle of Thermopylae where he led 300 warriors in a sacrificial last stand against the Persian army. This pivotal event shapes his core identity as a heroic spirit. Within Fate/Grand Order, his capabilities emphasize stalwart defense and leadership, mirroring his historical tactics. His Noble Phantasm, **Thermopylae Enomotia**, recreates the iconic Spartan phalanx, summoning spectral warriors to absorb enemy assaults and fortify allied defenses, embodying his unwavering resolve as a shield. His skills include **Rear Guard's Pride**, drawing strength from tactical disadvantages, and **Battle Continuation**, enabling him to fight on despite mortal wounds. Personality-wise, Leonidas balances disciplined kingship with Spartan fervor. He self-identifies as an "intellimacho" – a strategic mind leading inherently impulsive warriors. While lamenting Sparta's overall lack of tactical foresight beyond himself, he acknowledges sharing their "hot-blooded" spirit, prioritizing rigorous training and resilience above all. He exhibits fierce loyalty to worthy masters but reacts with intense fury to insults against Sparta. Contrasting this, he harbors a deep-seated fear of ghosts, a vulnerability starkly displayed during the Garden of Order event where he confined himself within Ogawa Apartments to avoid spectral entities. His story roles span multiple Fate/Grand Order narratives: * **Second Singularity (Septem)**: Summoned by antagonist Lev Lainur Flauros, he attacks protagonist Ritsuka Fujimaru's group under orders, ultimately facing defeat and death. * **Babylonia Singularity**: Summoned by Gilgamesh as one of seven Heroic Spirits defending Uruk against demonic beasts, he commands the Northern Wall's defenses, training soldiers and coordinating strategies. During the Nippur rescue, his diversionary tactics are thwarted by Kingu's betrayal. He sacrifices himself shielding Ritsuka and Mash from Gorgon's petrifying heat ray using Thermopylae Enomotia, recognizing Gorgon's true identity moments before his petrified body shatters. * **Event Appearances**: In a Christmas event, he obstructs Jeanne Alter Santa Lily's group as part of a trial orchestrated by the "mastermind." During Garden of Order, he resides in Ogawa Apartments until evicted due to his ghost-related confinement. He forms notable relationships: viewing fellow shield-wielder Mash Kyrielight with profound respect, feeling motivated to train rigorously to meet her perceived expectations. He senses kinship with Hector as a fellow defender, though laments Hector's disinterest in training. Under Gilgamesh's command in Babylonia, he collaborates closely with Servants like Ushiwakamaru and Benkei, leading Uruk's forces with tactical authority.