|◄ Preceded by|| Eren Kruger|
|Followed by ►|
|Unknown|| Grisha Yeager|
|There is no such thing as truth in this world. That is our reality. Anyone can become a god or a devil. All it takes is for someone to claim that to be the truth.|
|— Kruger about the variations of Ymir Fritz's story|
Eren Kruger (エレン・クルーガー Eren Kurūgā?) was an Eldian spy posing as a Marleyan officer in the Public Security Authorities. He founded the Eldian Restorationists, and used the pseudonym the Owl (フクロウ Fukurō?) to communicate. Secretly, he possessed the power of the Attack Titan.
Kruger was a fairly large, well-built, older man. He had shaggy dark hair with gray in it which he kept combed to the side. Kruger had a very slender face and pronounced cheekbones, and he was seen wearing the standard uniform for Marleyan soldiers and officers, although he only wore his uniform's hat when he was facing civilians. He also heavily resembled Eren Yeager as a young child.
As a Titan, Kruger's form shared some features with Grisha and Eren Yeager's Titan forms due to them all being of the same type; he had sunken eye sockets, was very muscular, and had long dark hair. However, his Titan form also shared some unique facial characteristics with his human form, such as his pronounced cheekbones. In addition, though his hair was long, it was noticeably neater than Grisha or Eren Yeager's.
Kruger appeared to be a largely stoic individual who never displayed any emotions, most likely as a consequence of enduring years of suffering and misery as a mole and being forced to commit brutal and atrocious acts against fellow Eldians. After finding Grisha and Faye Yeager outside of their internment zone, he felt no qualms in punishing Grisha physically. He again continued to show a lack of empathy when the Yeagers learned of Faye's death, remaining stone-faced at the sight of their sorrow.
However, in truth, he felt remorse for all of his immoral acts that he did to his brethren, but saw it necessary for the betterment of Eldia. Another notable aspect of his worldview was his relativistic belief; he denied the concept of an objective truth, claiming that everything was a matter of personal opinion.
Kruger was born to an Eldian family living in Marley. His father had joined an Eldian revolutionary army led by the remnants of the royal Fritz family who remained on the mainland. Unfortunately, the army was very ineffective, and its members, including Kruger's father, were captured and burned alive by the Public Security Authorities as Kruger hid in a closet. Afterward, he was rescued by friends of his father. Sometime later, Kruger was able to join the Public Security Authorities as a spy thanks to an Eldian doctor who was able to fake his blood tests as he had done for himself sometime earlier. As a spy in the military, Kruger would refer to himself in correspondence with the Eldian Restorationists as "the Owl," all while spending his military career turning thousands of Eldians into Titans over the years in order to hide his identity.
While spending his downtime watching blimps with one of his fellow officers, Kruger caught sight of Grisha and Faye Yeager following the blimp. Observing their armbands, Kruger deduced that they are from the Liberio internment zone. Because they had left their Internment Zone without permission, Kruger offered them a choice between hard labor or "physical punishment." Grisha nervously chose to take both his and Faye's punishment, and Kruger proceeded to savagely knee him in the stomach. Afterwards, however, Kruger showed a vague hint of empathy after allowing Grisha to stay with him to watch the blimp, citing that since he was here, he may as well see it. Kruger accompanied his fellow officer to inform the Yeagers of Faye's death and observed quietly as they grieved for Faye. Amidst the conversation, he looked into the traumatized Grisha's eyes, seeing pure hatred and a desire for revenge.
Thirteen years after inheriting his power, when the "Curse of Ymir" was beginning to take hold of his health, Kruger was present when Grisha was tortured by the Public Security Authorities. He asked if he confessed to the Owl's identity, and Grisha assured he did not know. Kruger announced the boat that will send the Restorationists to Paradis Island was ready.
During the operation at Paradis Island, Kruger escorts Grisha from the top of a thirty-foot wall, telling Grisha that as punishment for treason, he will be transformed into a Titan. Grisha tells Kruger that he remembers him from all those years back when his sister was murdered, with Kruger emotionlessly acknowledging this. He also calmly watched the Restorationists being turned into mindless Titans and chase after their comrade.
As it was Dina Fritz's turn to be transformed, Kruger violently silenced a yelling Grisha and held him in place. Both he and Grisha watched as Dina was turned into a Titan. When Gross was about to throw Grisha off the Wall, Kruger suddenly intervened and pushed his comrade off the wall, and revealed to a shocked Grisha that he was the Owl. While mutilating his hand, he taught Grisha how to use the power of the Titans before, in his Titan form, destroying the Marleyan steamboat and slaughtering all the remaining soldiers.
Kruger then set Grisha free and answered all the questions of the latter, justifying his deeds and telling him about his life. Before letting a determined Grisha inherit his ability in order to fulfill the Eldian Restorationists goal, Kruger revealed him the name of the Titan he would become and explained the history of the Founding Titan and King Fritz's vow with the Founding Titan renouncing all war. As he prepared to inject Grisha with a Titan serum, he urged him to find a family and complete his mission for the sake of Armin and Mikasa. Grisha was confused by these names, and Kruger admitted that he did not know whose memories he was seeing.
- Kruger bears an almost identical resemblance to Eren Yeager as a child.
- Eren Yeager would later use the name Kruger as an alias whilst in Marley in homage to him.