Kenny Ackerman was a member of the Military Police Brigade's First Interior Squad and the captain of the Anti-Personnel Control Squad. An infamous serial killer known for slitting his victim's throats, he was proficient at evasion enough to become an urban legend known as Kenny the Ripper. After meeting and befriending Uri Reiss, he worked for the crown, but secretly desired the "God-like power" that the Reiss family had possessed for himself.
He was the maternal uncle of Levi Ackerman and had taught the latter as a child on how to survive the Underground.
Kenny Ackerman was a very tall and slim man who appeared to be well-built. He had short, coarse-looking dark hair that reached to his neck and also had a thin beard along his jawline. He had the appearance of a middle-aged man with wrinkles around his eyes, which were small and piercing. He was mostly seen wearing a simple white shirt with a black tie that was never fully done up, and a large black overcoat that reached past his knees. He also had a bowler hat with a white band around it. He was almost always seen wearing a pronounced scowl, even when making a foul joke.
Appearance: Kenny Ackerman was a very tall and slim man who appeared to be well-built. He had short, coarse-looking dark hair that reached to his neck and also had a thin beard along his jawline.
Personality: Kenny wanted power, and his personality was molded around this goal. He was a ruthless individual who did not hesitate to do anything to get the job done, including murdering children or betraying his allies.
History: " In the decades prior to the fall of Wall Maria, Kenny was an infamous serial killer that stalked victims in Mitras. His preferred method of killing was to slit the throats of his victims, which earned him his infamous handle "Kenny the Ripper", and it was rumored that he murdered over 100 members of the Military Police Brigade.
Kenny Ackerman in the story: In the year 845, days after the fall of Wall Maria, Kenny arrives with a group of soldiers at Historia Reiss's home. He grabs Historia's mother and asks Rod Reiss if she and Historia are related to him. Rod Reiss denies it and Kenny slits Alma's throat.
Source: Attack on Titan Wiki, available under CC BY-SA 3.0.