Judge Death

Judge Death is an undead supervillain from the world of Judge Dredd and is in many ways what Dredd could of become if taken to the most extreme as he too is a merciless enforcer of law, however his version of the law is at odds with that of Dredd's world and thus makes him one of Dredd's many enemies - due to his popularity however Judge Death has taken on more than just Judge Dredd and was the antagonist of a Judge Dredd / Batman crossover as well as other tales that range from dark and sinister to downright comedic.

History
Judge Death originated in Deadworld, an alternate reality from that of the mainstream Judge Dredd series, in this world all life had been declared a crime since only the living can commit crime - as a Judge the appropriately named Death upheld the laws of his world with the same merciless efficiency as the Judges of the mainstream world but was also undead by default and a mass murderer intent on exterminating all life (a Judge is sworn to uphold law and punish crime - therefor by Death's twisted morality he is enforcing law by killing the living as the very act of existing has been outlawed in Deadworld).