Doomsday
While a relative newbie in the nemesis menagerie, Doomsday has a trump card that none of the others have—he killed Superman. Created by Krytonian scientists, this genetically enhanced superweapon was once locked away for the good of mankind and the universe, but escaped and made his way towards Earth. Once he arrived, Doomday carved a wave of destruction, which set up the battle of the century and culminated in the death of the comic book icon. Since then, Superman’s been reborn and Doomsday has yet to recreate such a feat, though he is still the only enemy that can lay claim to putting a nail in the coffin of the Man of Steel.
Brainiac
An extraterrestrial android with death-threatening capabilities, Brainiac was considered a menace to the universe by his creators and sent to conquer alien worlds. Upon his travels, he shrunk the Kryptonian metropolis known as Kandor, as well as other alien cities, for trophy purposes and further study. However, Superman often thwarted his special appearances on Earth. He has often joined forces with Lex Luthor as their mutual respect for intelligence and hatred of Superman made for a methodical and manageable alliance. The battle between Brainiac and Superman personified the theory of brain vs. brawn.
