Judge Mortis is one of the Dark Judges along side Judge Death, Judge Fire, and Judge Fear. He was once human, but turned into supernatural creatures by the Sisters of Death. With the other Judges of Death they decided that all life was a crime and started murdering everyone on their world. When done they started invading other dimensions and exterminating life where ever they could find it. The Judges of Death has acccomplish this with their tremendous power. Mortis himself has the power to bring decay and death to any living thing he touches.
The Dark Judges are the arch-enemy of Judge Dredd and appear in 2000ad and the Megazine.