|◄ Preceded by|| Karl Fritz|
Unknown, known as the First King from 743 afterward
|Followed by ►|
|Unknown, eventually Fritz||Unknown, eventually Rod and Uri's father|
|◄ Preceded by||Karl Fritz||Followed by ►|
|Unknown, eventually Ymir Fritz||Unknown, eventually Rod and Uri's father|
|Eldians...Titans...they never should have existed in the first place. I will accept the responsibility of righting this wrong. Only...until the day that this retribution comes, I want to live inside the Walls...I want to enjoy this brief paradise, this world without conflict.|
|— Karl Fritz's final words to the Tybur family, recounted by Willy Tybur|
Karl Fritz (カール・フリッツ Kāru Furittsu?) was the 145th king of Eldia and was the one responsible for its downfall. After the Eldian Empire's collapse, he moved many of the Eldians to Paradis Island where he raised the Walls, and used the power of the Founding Titan to erase the memories of the outside world from most people inside. Afterward, he changed his family name from Fritz to Reiss and became the first King of the Walls.
Karl Fritz was an aged man with long fair hair and a thick beard.
Karl Fritz's Titan form stood at 13 meters tall, like all other Founding Titans after Ymir Fritz. It had long, straight hair and sharp teeth. In contrast to its thick legs, the upper part of its body was quite skeletal, with its ribs visible through the skin. Its arms were thin and long, similar to those of the Beast Titan.
Karl Fritz was a man wracked with the guilt of his ancestors. Even before inheriting the Founding Titan, Karl Fritz detested the atrocities committed by the Eldian Empire. This intense guilt would lead him to conspire with the Tybur family to weaken Eldia enough for Marley, a nation long oppressed by Eldia, to conquer it and take back their land.
Fritz held the belief that the world would have been better off if Titans and Eldians never existed and he considered his people to be sinners. He believed that if the world decided to exterminate the Eldians, because the Eldians' sins are too heavy to be atoned for, it should be accepted.
Despite this, Karl Fritz and his successors still wish for their people to live in peace and happiness. So he created a "paradise" inside the Walls for them to live in, erasing his people's memories to make them ignorant and blissful, before the nations of the world would inevitably invade. He was fierce at defending the peace inside the Walls and feared the minority bloodlines he could not control; when the Ackerman family and the Azumabito branch clan refused to be silenced, he betrayed them and ordered their extermination.
Over a century before the Battle of Trost District, Karl Fritz was crowned the 145th King of the Fritz family and inherited the power of the Founding Titan. For many hundreds of years, various families subservient to the Fritz family were constantly at war with each other for control over the eight Titans, a civil war which Karl Fritz was ashamed of. Rather than following the method of his ancestors and using the Founding Titan to maintain order in the nation of Eldia, King Fritz conspired with the Tybur family, keepers of the War Hammer Titan, to lead Eldia on a path of destruction. Fritz and the Tyburs fabricated a hero of Marley, a nation long persecuted by Eldia, whose name was Helos. While the world was led to believe Helos continued to instigate the Eldian civil war, King Fritz moved the capital of Eldia to Paradis Island to the east of the mainland of their nation. In the King's absence, the Tybur family gave their support to the oppressed society of Marley, who took part in the Great Titan War in Eldia, gaining the power of seven out of the Nine Titans and rising up against their oppressors.
While war raged on the mainland, King Fritz gathered the royal family and the people of Eldia to the island. When humanity had gathered to Paradis Island, King Fritz used the power of the Founding Titan to guide countless Colossus Titans in the construction of the three concentric Walls Maria, Rose, and Sheena around the last remaining territory of Eldia in which the Subjects of Ymir could finally live in true peace.
When the Walls were completed, King Fritz gave an ultimatum to the outside world: if any act of war was committed against the remnants of Eldia, the tens of millions of Titans within the Walls would be unleashed upon the world to flatten the entire earth. However, this ultimatum was merely a bluff to ensure a lasting peace. In secret, King Fritz sent messages to his surviving relatives on the mainland as well as the Tybur family. Karl Fritz made a vow renouncing war with the Founding Titan, ensuring that he and his successors would never use its power for retaliation in the event that the Walls would fall under attack. If the day should come when Marley's power was great enough to destroy Eldia, his successors would accept it, though his final wish was to be given an age of peace to enjoy before Eldia's final retribution.
With the people of Eldia gathered within the Walls, Karl Fritz used his power again to alter the memories of all the Subjects of Ymir, erasing all knowledge about the world outside the Walls and the history before their creation. In order to protect the royal family, King Fritz renamed the royal family to the "Reiss family," who would live in hiding as nobles while a different bloodline would take the Fritz name. However, Eldians who were not Subjects of Ymir were unaffected by this manipulation, such as the Asian clan. To prevent the risk of these unaffected groups spreading information about the world beyond the Walls, King Reiss offered positions of nobility in Wall Sheena to these minority families, and most accepted the offer. However, the unaffected Ackerman clan and the Asian clan rejected King Reiss' ideology and turned against him. For this reason, King Reiss ordered for these families to be hunted down and exterminated.
To the east of Orvud District, King Reiss created a massive subterranean cavern where his successors would inherit the power of the Founding Titan. Sometime later, at the end of Karl Fritz's thirteen-year reign, he passed the Founding Titan to his successor. Karl Fritz had died, though his memories and his vow of renouncing war would live on in the Kings of the Walls for the next hundred years.
Throughout the generations, the ideology of King Reiss was carried through the monarchs of the Reiss family, and none would tell of the history of the Eldian Empire before the raising of the Walls. The King's beliefs would often manifest outwardly in his successors, such as Uri Reiss's desire for an age of peace before destruction and Frieda Reiss's view of the walled people as sinners.
Beyond the Walls, the actions of Karl Fritz inspired rebellion in Marley. The Eldian Restorationists, led by Eren Kruger under the alias "The Owl," sought to take the Founding Titan from the King of the Walls to finally rise up against their oppressors. The Restorationists believed that King Fritz was cowardly for abandoning his people in the Great Titan War, and by taking the Founding Titan they would restore the Eldian Empire to its former glory. Eventually, the movement was discovered and exiled to Paradis Island, though restorationist Grisha Yeager survived to carry out the mission. Inspired by Eren Kruger, who gave him his Attack Titan, Grisha entered into the Walls to begin his search for the Founding Titan.
During the fall of Wall Maria in the year 845, Grisha Yeager visits the Reiss Chapel where King Reiss' cavern was delved. Confronting Frieda Reiss, he begs for the King of the Walls to stop the attacking Titans for the sake of her people. The vow renouncing war would not allow her to retaliate, and Grisha's pleas are refused. Taking matters into his own hands, Grisha battles Frieda's Founding Titan with his Attack Titan and steals the Founder from her before slaughtering the rest of the Reiss family except for Rod Reiss, who escapes.
Fleeing the scene, Grisha gives his son Eren Yeager a Titan injection, passing the Founding Titan and the Attack Titan to him. With no royal blood in him, the Founding Titan becomes unusable and the King's vow of renouncing war is not passed on to Eren.
When Eren and Historia Reiss are captured and taken to Rod Reiss, Rod tells Historia the history of the Reiss family and the passing of the First King's ideology through the line of monarchs in the past century, preventing the truth of the world from being known to the people of the Walls.
During the battle of Shiganshina District, Zeke Yeager laments King Reiss' decision to take the memories of the Eldians away from them after the Great Titan War, leading them to make the same mistakes from the past.
In the aftermath of the battle, the survivors of the Survey Corps discover the basement of Grisha Yeager. In the basement, they find three journals describing his life before coming to the Walls. Through his story, the people of the Walls learn of the Eldian Restorationists' attempt to take the Founding Titan from the King of the Walls to end his vow of renouncing war. With this information, the military of Paradis Island decides to inform the people of the history that King Reiss took away from them a hundred years ago.
One month later, following the conclusion of the Marley Mid-East War, Willy Tybur hosts a festival in the Liberio internment zone set to conclude with a play in which he will reveal his plan to solve the Titan crisis. In this play, Lord Tybur reveals to the world that Karl Fritz himself was responsible for the fall of the Eldian Empire. However, Tybur further reveals that despite the age of peace King Fritz wanted between Marley and Eldia, their peace has come under threat due to the theft of the Founding Titan, now held by Eren Yeager.
- Titan Creation: Karl Fritz turned countless Subjects of Ymir into Colossus Titans.
- Titan Control: He used this power to control the Colossus Titans to build the Walls, by making them harden their bodies and confine themselves into the resulting structures.
- Memory Manipulation: He was capable of manipulating the memories of Subjects of Ymir. Other ethnicities, such as the Ackermans, the Asian bloodline, and the noble families, are unaffected.
- Memory Inheriting: He was able to pass down his memories to an unknown member of the Reiss family after dying, making them the inheritor of the lost memories of mankind. This also happened with all of the other inheritors, who inherited the memories of Karl Fritz and the inheritors themselves. However, they and all their subsequent heirs also inherited his belief that a world ruled by Titans would be "true peace." This influence is so strong that even people that wanted to stop the Titans changed their minds when they received the power, deciding not to make a move and refusing to reveal the reason, even to their own families.
- Power of the Titans: Little is known about his abilities as a Titan, except for the fact that he had enough control to retain his intelligence while transformed; since he was seen surrounded by a crowd of people without attacking them, and without any of those people trying to flee.