The four Dark Judges (who occasionally have their own strip in the Judge Dredd Megazine) are Judge Death and his subordinates, Judge Fear, Judge Fire and Judge Mortis, four once-human Judges who had themselves transformed by the dark magics of the witches known as the Sisters of Death into undead monsters in order to fulfil Judge Death's mission to destroy all life. Their reasoning is simple: all life is committed by the living, therefore life itself must be a crime.
The Dark Judges have repeatedly attacked Mega-City One, with their most notable success being the Necropolis incident, when they conquered the city and exterminated a huge chunk of its population, an estimated 60 million citizens (and temporarily inducted Dredd's clone brother, Judge Kraken into their ranks). They have always been beaten back eventually though, usually by either Judge Dredd or his associate, the psychic Judge Anderson. The series The Fall of Deadworld revealed that there were once many more Dark Judges, but Death and his three principal lieutenants now appear to be the only ones left.
