Bullseye

Bullseye can kill you with anything in the room. A pencil, a playing card, a wire hanger, a peanut. He has no powers, no origin he tells the same way twice, and no interest in money beyond what it buys him: permission to hurt people creatively. Marvel has deliberately kept his real name and history unconfirmed, because the not-knowing is the point. What is documented is his record, and it is the worst in Hell's Kitchen.

He is Daredevil's true opposite. Where Matt Murdock is defined by restraint, Bullseye is defined by aim, and he uses it to take away everything Matt loves. He killed Elektra with her own sai. He killed Karen Page with Matt's own billy club. Norman Osborn later put him in a Hawkeye costume and called him an Avenger, which is the single most cynical thing Dark Reign ever did, and it worked.

Marv Wolfman and John Romita Sr. created Bullseye in Daredevil #131 as a costumed hitman gimmick. Frank Miller turned him into a monster: Daredevil #181 has him kill Elektra, and Miller's Born Again era cemented the rivalry as the defining relationship of the book.

Kevin Smith's Guardian Devil and the Marvel Knights era leaned into his cruelty, culminating in the murder of Karen Page. Warren Ellis' Thunderbolts run put him on a government team under Norman Osborn, where his handler had to threaten him constantly to keep him in line.

Dark Reign gave him his highest-profile role: Osborn dressed him as Hawkeye and put him on the Dark Avengers, letting a mass murderer operate with federal sanction. Daredevil finally killed him during Shadowland, though Marvel later brought him back, as it always does.