Uri Reiss (ウーリ・レイス Ūri Reisu?) was the younger brother of Rod Reiss and the paternal uncle of Frieda Reiss and Historia Reiss. He was the true king of the Walls for some time until the year 842 and was Kenny Ackermann's best friend. He inherited the Founding Titan from his father, and passed it along with the crown to his niece, Frieda Reiss.
He was a frail man who usually wore a simple light colored robe. He had neck length, dirty-blond hair. He also had light, weary eyes; with a calm, wise beyond his years type of expression. After inheriting the Founding Titan, Uri's eyes would change between their normal light color to a purple look, which meant he was bound by the will of the First Reiss King. Like most of the Reiss family, he was also rather short.
Despite his upbringing and his responsibilities, he disagreed with his father's policy to keep humanity in bondage to the Titans, believing that their family should use their power to eliminate the Titans and return the world to mankind. He was brave enough, and held his ideals strongly enough, to volunteer to be the one to inherit the Founding Titan from his father, despite the risk of becoming possessed by his ancestor's ideology.
He refused to hold a grudge against Kenny, despite the latter's rudeness and repeated attempts to attack him; believing that because of the Reiss family, the Ackermann's hate was justified. He even went so far as to bow down to Kenny and formally apologize.
He was also a very calm man. He did not show any signal of pain when Kenny hurt him with a knife and he did not hesitate when Kenny aimed him with a pistol.
Even though he could not rid the world of Titans as he originally wanted, he truly cared about everyone. He wanted to make a paradise for the remaining members of humanity, believing not far in the future that their world would fall.
Uri was the second born of Mr. Reiss and younger brother of Rod Reiss. As their father was the inheritor of the Founding Titan, the "invincible power" that could stop the terror of the Titans once and for all, Uri and Rod pleaded with him to free humanity from their encagement, but he always refused to do so or to explain why he would not.
Sometime later, Uri volunteered to be the next Founding Titan with the full intention to use it to stop the Titans, and according to Rod, he requested him to pray; as the amount of power the Founding Titan would give him would effectively make him a god.
However, after Uri inherited the power of the Titans and memories of the world from their father by eating him in the succession ritual of the Reiss family, Rod could tell by his eyes that he had inherited that same ideology; and as Mr. Reiss and all the other kings before them, Uri refused to either stop the Titans and to tell everyone the lost memories of mankind.
After Uri inherited the Founding Titan, Kenny Ackermann discovered that Uri was the true king, and tracked him down and tried to kill him. However, he was stopped by Uri, who caught him on his Titan form. Kenny did not give up after this, even throwing his knife at Uri and pointing his gun at him. However, even after this and the fact that Rod insisted that Kenny had to die, Uri spared his life. He said that as an Ackermann, he deserved to point his knife at him, due to the persecution that the monarchy had plotted against them.
After this, Uri, with the knife still stuck in his arm, bowed before Kenny and apologized because of the persecution of his family and his frustrated attempt to create a paradise within the Walls. This heavily surprised Kenny, who wondered how a powerful King like him could bow before someone like himself.
From that point on, Kenny became not only his bodyguard, but also a close friend, and Uri ceased the attack on the Ackermann bloodline. The two spent much time together talking, with Uri even telling him that his power will soon be inherited by Frieda Reiss.
Sometime after this, Uri was chained hand and foot underneath the Reiss Chapel as his successor, Frieda, sobbed and injected herself with the Titan syringe. His brother, sister-in-law and nephews witnessed his death. He smiled as his 15-year-old niece Frieda transformed into a Pure Titan and ate his upper body, inheriting his position, the power of the Titans, memories of the world, and will of the First King.
Many years later, as Rod is trying to convince Historia to eat Eren and become the next Founding Titan, he tells her about Uri, their unsuccessful attempts to convince their father to stop the Titans, and how Uri had requested him to pray before receiving the Founding Titan. Rod prays to Historia in the same fashion, but she does not believe his story and throws him to the floor, calling him a liar.
While dying, Kenny ponders about his mutual past with Uri, as well as their friendship.
- Kenny Ackermann - After witnessing the humility Uri showed a lowlife like him, Kenny developed a deep respect and admiration for Uri. The two became friends, with Kenny being impressed by Uri's empathy and compassion, going as far as wishing to inherit Uri's Founding Titan in hopes to become such a compassionate person himself. Kenny saw Uri as the most powerful being, believing that only a being with such immeasurable power could allow itself to feel such compassion for others like Uri did. Even after his death, Kenny remembered Uri fondly, as he threatened to kill Rod after the latter called Uri a whimsical person.