Quirkless

The label covers people with no ability, no unusual features, and nothing that would place them under any superhuman classification. Before powers spread across the globe they were simply normal and vastly outnumbered those with Metas; generations later the ratio inverted completely. Reactions vary by society and by circumstance. Izuku Midoriya drew relentless mockery and prejudice, while Melissa Shield attracted pity yet kept warm relationships with powered friends. The common assumption is that a person without a Quirk is weak, worthless, or grotesquely unlucky.

Heroics is treated as closed to them, though nothing formally forbids it, since the work demands facing Villains in lethal situations. Pro Heroes stripped of their abilities usually resign as unfit for duty, as O'Clock and Ragdoll did, although Mirio Togata intended to keep working while temporarily powerless. Other careers stay open: Kyudai Garaki built a strong reputation as a doctor while his official records listed him without a Quirk. No Quirkless villains are known either, largely because the legal definition requires using a power to break the law, leaving such criminals to the Police Force outside of extreme cases.

Quirklessness reads as recessive. A child with even one powered parent stands a better chance of inheriting something, yet two carriers can still produce a Quirkless child, as Izuku's parents did when he took neither of their abilities nor any blend of them. The pinky toe serves as a rough marker, since two joints there almost always accompany the absence of a power, suggesting a tight chromosomal link.

Carrying no Quirk Factor turns out to be a shield. Bioweapons that overdrive powers, such as Trigger Bombs, pass over them harmlessly. Erasure finds nothing to suppress. The Quirk-Destroying Drug has no target. One For All's life-force drain does not apply, and the Quirk Singularity is irrelevant to them. The immunity holds only while the body stays empty; introduce a Factor and it weakens sharply or vanishes.

Powers can still be acquired late, though rarely. A transferable ability like One For All can be handed over, but an unprepared body has to be conditioned first, which is why Izuku spent so long building the muscle to carry stockpiled raw power. All For One can implant an ability outright, sometimes leaving the recipient mindless, sometimes leaving them dependent on support gear as Yuga Aoyama's belt shows. DNA injection offers a third route, granting a donor's power at reduced efficacy and requiring compatibility: Kuin Hachisuka borrowed Electric Eel from a blood sample, and Nine received a copy of All For One capped at eight stolen abilities.

Losing a Quirk works several ways. Destroy the anatomy housing the Factor and the power goes dead, as with Kai Chisaki's amputated arms or Shota Aizawa's lost eye. Drugs built from Eri's genetic material rewind a Factor to a state predating the whole phenomenon. Theft by All For One removes the Factor entirely, which is why Rewind can undo the drug but cannot restore a stolen power. One For All leaves behind embers that eventually burn out, retiring All Might and, after the Final War, returning Izuku to where he started.

Izuku Midoriya is the defining case, born with nothing, gifted One For All by All Might, and left holding fading embers after forcing the Quirk and its assimilated abilities into Tomura Shigaraki; they flickered out around the time he graduated from U.A. High School. Toshinori Yagi walked the same arc a generation earlier, inheriting from Nana Shimura and spending the last of it against All For One. Melissa Shield never held a power at any point, the only major character of whom that is true, and Yuga Aoyama is the only known Quirkless person given an ability, Navel Laser, who kept it.

Many lost what they had. The twins' mother never knew she carried Spearlike Bones before her eldest son took it as she died. The Luminescent Baby, Iwao Oguro, Tomoko Shiretoko, Cathleen Bate, Keigo Takami, and Chizome Akaguro all had their powers stolen by a wielder of All For One. Tomura Shigaraki is unique in being robbed as an infant and then secretly issued a replacement, Decay. Yoichi Shigaraki passed his own on to Toshitsugu Kudo unwittingly at the moment of his death. Mirio Togata stands alone in losing his to the Quirk-Destroying Drug rather than to theft, and in getting it back through Eri's Rewind.

A separate group counts as functionally Quirkless, retaining a Factor they can no longer use. Kai Chisaki and Shota Aizawa belong here through mutilation. Giulio Gandini lost the arm holding Neutralization before Anna Scervino's Overmodification restored and augmented it, and Anna herself had her own power permanently suppressed by Giulio, the only such case not caused by bodily damage.