Izuku is very short for his age, his round face framed by a short mess of fluffy dark green hair which sticks up at odd angles around his head, casting noticeably dark shadows onto itself. His eyes are large and somewhat circular, their irises the same green color as his hair, and are usually stretched quite wide, giving him an innocent appearance. He has a set of four symmetrical freckles in diamond formations, one on each cheek, but despite these prominent traits, he is often described by others as being plain-looking. Though he was initially very skinny, Izuku has gained an array of toned muscles after his ten months of extensive training with All Might, and as the series progresses these are shown to become more developed and defined as he gradually grows stronger.
After his battle against , the fingers on his right hand became slightly deformed, and his hand shows scarring. His right arm was further damaged after his fight with , leaving various other scars all over it. Following his recovery after said fight, Izuku wears a black compression sleeve on the upper portion of his right arm in order to support the heavy damage it sustained: it is partially visible when he wears short sleeves. During his days, he wore a plain black uniform with yellow buttons, accompanied by white sneakers. While at home, he wears a green over a white shirt and gray sweatpants.
At U.A., he wears the standard male uniform: a light gray blazer with dark turquoise trimmings over a white dress shirt and dress pants, along with a red tie which he doesn't do up properly, leaving it much shorter than it should be. Instead of the plain brown shoes worn by the majority of the student body, he usually wears oversized red boots with thick white soles, laced up to the top. Izuku's original hero is a green full-body jumpsuit with a red belt, elbow pads, knee pads, and gloves, along with his signature red boots. He also wears a mask with long ear-like protrusions that resembles All Might's haircut, and a respirator with a makeshift smile on it that also reflects that of the said hero. The costume was severely damaged as a result of his first battle against and has to be repaired, which is why, during the and , Izuku had to wear the U.A. gym uniform. This attire consists of a dark blue high-collared tracksuit with thick white lines over his torso and down his legs, forming the letters "U" and "A", and along with this, a respirator.
His second hero costume has a few changes and now looks sturdier and more combat-ready in appearance. The knee pads have been extended to his legs and reach up to his thighs, and his new gloves are tinted beige and are decorated with blue stripes. His respirator is now metal, diamond-shaped, and has eight holes. Izuku goes without a mask in his second suit, and although the mask is still present, he doesn't wear it much. During the , Izuku had his costume upgraded again to suit his new fighting moves Shoot Style, by adding iron soles to his red boots to increase the power of his kicks. Arm braces were added, and his knee pads now have yellow bolts fastened into them (they were originally added in his second costume in the manga). Sometime later, just before the , creates support gloves to better help him use his powers for long-range attacks. Following the , Izuku adds the gloves to his hero costume and uses them in combat. Of all Heroes, the Symbol of Peace has impacted Izuku's life the most, seeing as how Midoriya models himself after the former Number One Hero. Many of Izuku's decisions and actions result from his desire to become a Hero similar to All Might, and thus he has a great devotion for him, to the point of collecting several pieces of various Merchandise related to the Hero and emulating several of his traits. Having inherited his , one of Izuku's current priorities is to be able to live up to his idol's legacy, as he is always looking for ways to improve his usage of One For All, being aware of the immense pressure that comes with succeeding the greatest Hero of all time.
Izuku appears to have a more brash and abrasive side to him. This typically shows up when he finds himself in combat. This side of him makes him act more like Katsuki, being rather loud and unwavering, and also with a strong drive towards victory. He claims that this is because he sees Katsuki as the embodiment of what someone who strives for victory should be. He has also admitted that he doesn't like this side of him very much and tends to keep it in check. Izuku's intelligence, heroism and courage are seen to regularly boost the morale of his comrades, which has made him inadvertently along Katsuki, one of Class 1-A's unofficial vanguards. Something noted by Aizawa. Izuku is a caring person and never hesitates to rescue someone in danger, even if he knows that he is not strong enough to do it. Often, he does this on a whim, taking a more careless approach than the usual overthinking he goes through. Izuku often helps people with personal and emotional problems, even if it does not concern him, claiming that a Hero should meddle in other people's lives. Still, his heroic spirit is recognized by many, having earned the loyalty and gratitude of characters that were previously antagonistic to him such as , Shoto and even the , acknowledged Izuku as a true hero.
