The Dark Judges - Judge Death, Judge Fire, Judge Fear, and Judge Mortis.
Once human, but turned into supernatural creatures by the Sisters of Death. They decided that all life was a crime and murdered everyone on their world before invading other dimensions and exterminating life there.
The Dark Judges are the arch-enemy of Judge Dredd and appear in 2000ad and the Megazine.
Judge Fire was once know as Fuego, an undercover Judge who earned his name after burning down a school for breaking noise regulations at playtime. Judge Fire became a Dark Judge after being killed and resurrected by Judge Death.