Levi has short, straight black hair styled in an undercut, as well as narrow, intimidating dull gray eyes with dark circles under them and a deceptively youthful face. He is quite short, but his physique is well-developed in musculature from extensive vertical maneuvering equipment usage. He is usually either frowning or expressionless; that, plus his extremely calm demeanor, often makes it difficult for others to guess what he is thinking. He is most often seen in his Survey Corps uniform, with a light gray button up shirt underneath along with his trademark white ascot. When embarking on expeditions outside the Walls, he also wears the Survey Corps' green hooded cloak. Once, when forced to take leave from his duties due to injury, Levi was seen in a black suit, plain white shirt, ascot, and dress shoes. However, since the beginning of the coup d'état, he has left the ascot off. For most of the time during which the Survey Corps were on the run from the military and monarchy, he simply wore his vertical maneuvering equipment harness over casual clothes. Levi is described as a "clean freak" by those who know him personally, as he prefers his environment and himself to be spotlessly clean. He is averse to having either himself or his equipment soiled, and has been known to wipe down his blood-smeared blades while still on the battlefield. However, he will not hesitate to touch filth if he deems it necessary.Despite his preoccupation with cleanliness, Levi is not very approachable. He rarely shows emotion, giving a cold impression to others. His manner of speaking tends to be very blunt, even insulting, and his comments are often coarse or inappropriate. He is not above provoking or belittling those who oppose or irritate him. His sense of humor tends toward the vulgar, insulting, and dark. All of this makes him unsettling to a great number of people.
In his pre-Survey Corps criminal life, when he lived in the Underground City, Levi refused to take orders from anyone (as Petra Ral tells Eren), though he placed a great trust in his comrades, something he would later do with his subordinates. However, after he joined the Survey Corps, he came to greatly respect Commander Erwin Smith, whose orders he follows willingly because he trusts in Erwin's vision for the Corps. Levi's obedience is strictly limited to individuals he respects, and he has no problem showing open disdain for authority from anyone outside of this circle. At Eren's tribunal, he insulted the merchants by calling them "pigs" and told the Military Police that they were not competent enough to handle Eren, mocking several MPs by observing that they have never battled or even seen a single Titan. He even sardonically suggests that they join the Survey Corps, which caused them to back off. He openly resents most of the MPs for their continual attempts to undermine the Survey Corps, and also presumably because of the criminal life he led before he joined the Corps. Although he rarely shows it, Levi has a strong sense of morality and empathy. One of his most defining characteristics is the great value he places on preserving human life; this is especially shown when it was revealed that all Titans might have once been human themselves. The thought that he had unknowingly been killing humans all this time disturbs him greatly. Though he bore no malice against Eren, he was willing to resort to violence in order to save his life at his tribunal, eventually asking Eren whether he resented him for the beating. Levi himself has stated that he hates unnecessary casualties, and he tells his subordinates to use their judgment so that they can avoid blunders that may cost them their lives. Because of their hazardous profession and his personal values, he cares greatly for his subordinates' welfare. This is seen several times: when ordered to retreat early to Wall Rose at the end of the disastrous 57th Expedition, Levi was visibly distressed that so many of his soldiers had died on a fruitless mission. Later, he risked his life against the Female Titan in order to retrieve Eren from her mouth and also to protect to Mikasa, who had gone after her recklessly looking for vengeance. As they re-entered the gate, Petra's father approached him, cheerfully talking about his daughter and her unwavering devotion to the Survey Corps. Unbeknownst to him, his daughter had just been killed; Levi remained silent, he was too overcome with grief to reply. Levi was visibly affected by the loss of his entire original Special Operations Squad at the hands of the Female Titan, stating that he carries the will of his fallen comrades, and that their collective grudge against the Titans further strengthens his resolve to continue to fight. Despite his obedience to Erwin, Levi operates rather independently. Many of his Titan kills are solo, accomplished with little direct cooperation from other soldiers (due to him usually assigning them to hunt other Titans in the vicinity). Although he is looked up to by many, and he does not hesitate to give orders when necessary, Levi does not see himself as a leader in the same way Erwin is. He does not seem to have much use for hierarchy in general, and he leaves decisions up to his subordinates as often as he can. Though Levi is aware that his battle skill is in a different league from that of almost any other human soldier alive, he is not particularly arrogant about it, as he knows from experience that no human soldier is invulnerable. Few will argue with his claims that only he can handle certain difficult tasks, because he has proven his ability to accomplish them. While Levi shows loyalty and empathy for his comrades, he shows no mercy towards the Titans, slaughtering them indiscriminately with obvious indifference. When dealing with individuals he perceives to be enemies to mankind, Levi is capable of behaving sadistically, even vindictively. For example, when the Female Titan was captured, Levi told her he enjoyed watching her suffer and described in chilling detail how he intended to mutilate her human body. He has also tortured Djel Sannes with Hange Zoë, punching him and twisting his already broken nose. Levi is occasionally known to lose his calm demeanor and to use threats or violence to get others to listen to him, even if they are fellow members of the corps. An example of such behavior was shown when he directly ordered Historia Reiss to take on the role of queen when the question was presented to her. When she shakily says she is unfit, he grabs her and lifts her off the ground, choking her and telling her to fight back if she does not like it. He then drops her and yells at her to make her decision, but is however calm once again when she complies with his demands.