Gashly Eijiju

A top hat and a cloak, both black, swallow almost everything about him, flattening the tall, slender figure underneath into something closer to a shadow than a man. A white mask sits over the face, punched with holes that presumably let him see out, though no eyes are visible through them. Arms and legs stay lost in the same darkness, yet he still manages to hold things: a black umbrella kept permanently over his head, and a book. When an attack finally knocked the hat loose, short light-colored hair turned up beneath it.

Little of the man is ever spelled out, though the crimes speak plainly enough. Wrecking whole districts with his Quirk marks him as dangerous and cruel, and Tartarus was the answer society settled on. He carries himself as a gentleman, stoic and mannered, holding that umbrella steady through a heavy rainstorm. Reading is a habit he refuses to interrupt, even mid-battle, because his Quirk handles the fighting without him. Solo work suited him, but the debt of being pulled out of an inescapable prison bound him to All For One, and he swore himself to that cause.

His method was attrition. Rather than trade blows, he buried opponents under numbers until they collapsed, and the fact that his Quirk dressed those numbers up as infants made the terror worse. Panic and hysteria followed him through society until the Heroes finally put him down, took him in, and locked him away for it.

While he sat in Tartarus, All For One used Tomura Shigaraki's body to breach the facility and cut himself loose. Gashly walked out in that same wave, alongside high-level names like Kunieda and Dictator, invited to join a march toward becoming the greatest Demon Lord.

He stayed out of sight until the Final War arrived. All For One then warped him onto the field alongside the whole Paranormal Liberation Front, while the Heroes came in through a Warp Gate of their own. The Troy system snapped shut, caging most of the villains, Gashly included, and Warp Gate scattered the cages across the country. He landed at Takoba National Stadium, where the Heroes waiting on him were Ryukyu, Thirteen, Kosei Tsuburaba, Mashirao Ojiro, Rikido Sato, and Hanta Sero.

One by one the other fronts closed until only Takoba and the Mt. Fuji clash between Izuku Midoriya and Tomura remained. Once the stadium's remaining villains had all been beaten, Gashly finally opened up, pouring out an unending horde of puppet infants to drown the Heroes there. They were struggling badly when the army Eraser Head had assembled arrived through a Warp Gate. Distracted, he never saw Setsuna Tokage and Togaru Kamakiri drop on him from above, and a two-pronged combo knocked him cold. Ectoplasm and others closed the fight out.

Consider what it took. Tartarus held few inmates more dangerous, and All For One kept few assassins deadlier. A stadium full of Heroes was being ground down by his Quirk alone while the man himself did nothing more strenuous than turn pages. His unnamed ability spawns swarms of infant-like puppets rising from a dark mist beneath him, varied in shape and size and rubbery enough to stretch and deform without tearing. The book in his hands is implied to be the instrument that summons and steers them.