Demise (James Spector) is a fictional character from the Wild Cards book series. He was created by Walton Simons, and first appeared in the story "If Looks Could Kill" in Wild Cards II: Aces High.
In 1985, Spector was struck by the Wild Card virus and brought to the Jokertown Clinic, where he was seen by Dr. Tachyon. Tachyon had been working on improving his "Trump Card" countervirus, which had a low success rate, and injected Spector with an experimental version of the Trump, as well as subjecting him to an experimental tissue-regeneration process. It was seemingly unsuccessful; Spector's body experienced the failure of numerous organs, and he was pronounced dead. However, shortly after, he awoke screaming... and continued to scream for several months. Eventually, he got back enough of his sanity to escape (although he constantly feels the agony of his death), killing a nurse with his new-found power in the process.
In 1986 he was found by the cult leader known as The Astronomer, who offered to erase his unbearable memories of Death if Spector worked for him. Giving Spector the name Demise, the Astronomer used his death-powers in the ritual killings that charged the Astronomer's powers, and used him as an occasional assassin as well. When Demise eventually realised the Astronomer was just stringing him along, he rebelled, and when the Astronomer was weakened after his battle with Fortunato, Demise finished the old man off, leaving him embedded in a brick wall.
After this, Demise became a freelance assassin while looking for opportunities to kill Tachyon, until he was hired to do a job at the 1988 Democratic National Convention. There, his head was cut off on live national television by the psychotic Ace Mack the Knife. Mackie used his vibrational powers to remove Demise's head - only for the decapitated head to open its eyes and kill Messer explosively. Later, Dr. Tachyon examined Demise's body in the morgue and saw that he was actually starting to grow a new head. Tachyon immediately ordered his body cremated, to ensure that he would not return from death a second time.
Demise's body repairs itself so perfectly that he can even return from death. He has healed from bullet wounds and broken bones in seconds, and regrown lost limbs and other body parts. However, his body draws from its own current mass to reconstruct major damage, such as the loss of a limb, thus weakening his overall health until he has sufficient time to recover. He is also at risk of long-term damage from improper healing; the Astronomer once had Demise's forearm broken and then forcibly held out of proper alignment so that the bones knit improperly, rendering the limb nonfunctional below the elbow.
Demise can also telepathically project the "memory" of his death experience into other people, causing them to die as well, but he must look them in the eyes to do so (thus he can be foiled by things such as mirrorshades or insectoid multiple eyes). He can kill in seconds, stretch it out slowly for a very painful death, or give someone just enough to stun or disorient them. His power also prevents someone from looking away once he has locked eyes with them.