Professor Thaddeus Killgrave

A mad-scientist type lurking in the shadows of Metropolis, Professor Thaddeus Killgrave made his debut in Superman #19 in 1988, introduced by the legendary John Byrne during his celebrated reinvention of the Man of Steel. Though his catalog footprint is small — just three appearances spread across Action Comics, Superman, and Superman: Metropolis — he keeps genuinely rarefied company, crossing paths with Superman himself alongside Lois Lane, Jimmy Olsen, and even the interdimensional imp Mr. Mxyzptlk. A Copper Age creation with a name that practically crackles with villainy, Killgrave is one of those deep-cut DC figures that reminds devoted collectors just how richly populated the streets of Metropolis have always been.