Karl Fritz

Age shows plainly in Karl Fritz's human form, with pale hair worn long and a heavy growth of beard. His Founding Titan reaches the thirteen-meter height common to every inheritor after Ymir Fritz. Straight hair hangs around a mouth of pointed teeth, and while the legs are powerfully built, the torso above them looks starved, ribs pressing through the skin. Slender, elongated arms give the form a silhouette close to the Beast Titan's.

Guilt governs everything Karl Fritz does. Repulsed by his ancestors' conquests even before taking the throne, he comes to see Titans, and the Eldians who wield them, as a mistake the world should never have suffered. He regards his own people as sinners and holds that if the nations one day rise to wipe Eldia out, that judgment ought to be accepted rather than fought.

Yet the same king wants his subjects to know happiness first. The Walls exist to grant them a short, blissful paradise, kept ignorant of the reckoning he believes must come. That mercy has hard limits: bloodlines his power cannot reach frighten him, and when the Ackermans and the Asian clan refuse to fall silent, he orders both hunted toward extinction.

Crowned Eldia's 145th monarch over a century before the series' main events, Karl Fritz inherits the Founding Titan along with a nation whose vassal houses endlessly slaughter one another for control of the eight lesser Titans. Ashamed of that legacy, he plots the empire's fall alongside the Tybur family, holders of the War Hammer Titan. Together they invent Helos, a fictional Marleyan hero, while the king quietly relocates Eldia's capital to Paradis Island. With Tybur backing, Marley rises through the Great Titan War and claims seven of the Nine Titans.

Fritz gathers the Eldians who follow him onto the island and works the Founder's power on a staggering scale, turning masses of his own people into Colossus Titans and directing them to harden into three concentric barriers: Maria, Rose, and Sheena. He then warns the world that any aggression will release tens of millions of Titans sleeping inside those Walls, a threat he never intends to carry out. In secret he tells the Tyburs and his mainland relatives that he has sworn a vow renouncing war, binding himself and every later inheritor against retaliation, asking only that his people enjoy their brief paradise before Eldia's final retribution arrives.

A second exercise of the Founder's power strips all knowledge of the outside world from the Subjects of Ymir inside the Walls. Minorities immune to the rewrite are bought off with noble rank in Wall Sheena, the royal line hides beneath the new surname Reiss while unrelated stand-ins carry the Fritz name, and the defiant Ackerman and Asian clans are marked for purging. Beneath ground east of Orvud District he prepares the cavern where his heirs will pass on the Founding Titan, and at the close of a thirteen-year reign he dies, his memories and his vow flowing into a hundred years of successors.

That inherited ideology shapes everything after. It surfaces in Uri Reiss's longing for a gentle end and in Frieda Reiss's talk of sinners, and it paralyzes Frieda when Wall Maria falls, letting Grisha Yeager steal the Founder and pass it to Eren, over whom the vow holds no power. In Marley, restorationists brand the vanished king a coward and scheme to reclaim what he abandoned. The truth of his bargain finally reaches the public through Rod Reiss's account to Historia, the journals found in Grisha's basement, and Willy Tybur's stage play, which names Karl Fritz as the author of Eldia's downfall.

As a Titan he kept his full intelligence while transformed and commanded the Founder's signature powers at an advanced level: creating Titans from Eldians, controlling them en masse, rewriting memories across the Subjects of Ymir, and passing his own memories, convictions included, down the Reiss line after death.