Levi Ackerman is the captain of his own squad in the Survey Corps and is widely known as "Humanity's Strongest Fighter".

Levi has short, straight, black hair, parted to the right side, and narrow, frightening, dull gray-blue eyes with dark circles under them from lack of sleep. He is short in stature, but has well-developed muscles due to frequent use of the omni-directional mobility gear (ODM). Levi usually either frowns or remains expressionless, which, coupled with his extremely calm demeanor, often makes it difficult for others to understand what he is thinking.

He rarely shows emotions, making a bad impression on those around him. His manner of speech is blunt, rude, and full of insults, and his comments are often rude or inappropriate. He is not afraid to provoke and humiliate those who oppose him or irritate him. His sense of humor tends toward the vulgar, offensive, and dark. All this makes him very difficult to communicate with for most people. Although Levi rarely shows it, he has a sense of morality and empathy. He places great importance on preserving human life, so he tells his squad to use all their wits to avoid making mistakes that could cost them their lives. Levi is cruel and cold-blooded towards the Titans, killing them indiscriminately with apparent indifference.

Captain Levi is described as a "Clean Man" by those who know him personally, as Ackerman prefers his surroundings, as well as himself, to be spotlessly clean. He does not like to get dirty, and is known to wipe his blood-stained blades while still on the battlefield. However, he will not hesitate to touch the dirt if he deems it necessary.

After his mother's death, Levi was forced to live in the slums, turning to crime. Levi was raised by his uncle, Kenny Ackerman. During his life of crime in the slums before joining the Survey Corps, Levi refused to take orders from anyone, although he trusted his comrades very much. However, after joining, Levi came to have great respect for the Commander-in-Chief of the Survey Corps, Erwin Smith, whose demands and orders he followed without question. Levi also trusts his subordinates.