Dr. Kane (often refered to simply as "Kane") is a major villain in the anthropomorphic webcomic Jack and is unique in the fact that he is the only human to appear in the comic - indeed he is one of the few humans confirmed to exist at all in Jack's world, which is inhabited mostly by anthropomorphic animals.

In life Dr. Kane was a weapons-grade micro-biologist and seemed to have an obsession with immortality, having created a machine that could bring the dead back to life, other details of Kane's former existence are blurred at best but he is suggested to have links to Jack and Central - he may of been the man responsible for Central's death but this has not been officially confirmed yet.

What is known for certain is that in death Kane has become the Sin known as Envy and unlike most of the other demons of Hell he doesn't actively torture others - instead he has a grand and shadowy plan involving an army of Rework Zombies and the other Sins, who he is trying to get on his side for what may well be an attempted takeover of Hell itself.

Although human in life in death Kane's form is altered somewhat and more closely resembles a missing-link or other primate, having long arms and a hunched form as well as excessive body hair.