The Birth: Miles Warren was a brilliant scientist and professor at ESU. Miles had haboured a crush on Peter Perker's late girl friend; Gwen Stacy. When Gwen was killed by the Green Goblin, Miles Warren blamed Spider-Man for her death and went off the deep end. When his attempt to kill Spidey by sending the Punisher after him didn't work, he tried to clone Peter Parker and Gwen Stacy. At about this time Warren donned the identity of the Jackal to personally do damage on Peter Parker.
Miles Warren made his first appearance in Amazing Spider-Man #129 and took up the role as the Jackal in Amazing Spider-Man #149.

The Alter Ego: Miles Warren, doctorate, was a brilliant scientist and professor at the Empire State University. A bachelor, he was in love with Gwen Stacy, Peter Parker's ex-girlfriend. It was the mental trauma caused by Gwen's death that made Miles Warren lose his sanity. After that, it was just downhill for him. Though he made several advances in the science of cloning, his experiments never made the news since they were used in his clandestine war against Spider-Man.

The Legend: After Gwen Stacy's death, Miles Warren tried in vain to clone both Peter and Gwen. Unfortunately, the degenerated and died. His first victory came later when he sucessfully cloned Spider-Man. But the cloning process was flawed and the clone developed scars and became unstable. After escaping from the Jackal, the clone went by the name of Kaine. The Jackal tried to clone Spidey again after that and in the process created Spidercide. With his cloning techniques improving, Jackal was able to create a perfect clone of Peter Parker.
Somehow he was able to render Spider-Man unconscious as well as his clone. When the two awoke, they both believed they each of them was the real Spider-Man and they battled each other. A Spider-Man is a Spider-Man - when they found out that Miles had kidnapped Ned Leeds and had wired him to a bomb, they rushed in to save Ned. In the end, Warren himself; persuaded by a Gwen clone, saved Ned just before the bomb exploded, killing the mad proffessor. Also presumed dead in the exploion was one of the Spider men.
The only standing arachnid left the clone's body in an industrial smokestack and went home, convinced he was the real Peter Parker. But the clone was not dead and he became Ben Reilly a.k.a The Scarlet Spider.

What no-one knew at the time was that the Jackal had been busy creating clones of himself as well. Jackal's first Miles Warren clone was kept in the tank too long and developed a virus which transformed him into Carrion - a beast that made Spidey run around quite a bit.

The original Jackal wore an tight-fitting Olive Green costume with a slightly furry appearance to it. Dr Warren was remarkably well muscled. The outfit had razor-sharp claws which were typically tipped with some sort of drug. Physically he was no real match for Spider-Man, but with planning, psychology, and by enlisting several allies he was able to overcome Spider-Man on numerous occasions.
The recent Jackal is a genetically engineered clone of the original. The teeth and fur are no longer a costume. The new version is physically far superior to Spider-Man. Regardless, both the original and the new Jackals were worthy foes for Spider-Man.

The Jackal could also transplant memories and hidden hynotic suggestions into a persons mind. Spidey discovered this after the Jackal's death, when he felt an urge to kill his wife Mary Jane. The Jackal had implanted the suggestion in Pete's mind - he could not rest until Mary Jane was dead.

Amazing Spider-Man #149