Man-Spider is a monstrous version of Spider-Man, usually resembling a giant anthropomorphic spider clad in the shredded remnants of Peter's costume.
Spider-Man: The Animated Series
When Spider-Man's body began to mutate further he sought out the help of Dr. Mariah Crawford who gave him what she believed to be a cure. However, it accelerated the changes and he grew four extra arms, for a total of eight limbs, six arms and two legs. Peter still felt he needed to capture Michael Morbius, and then the Punisher arrived to kill Spider-Man, believing the media. Spider-Man eventually mutated further into a creature dubbed "Man Spider".
Man Spider had feelings from Peter but did not seem to possess any of Peter's memories. Man Spider continued searching out Morbius while fighting the Punisher. Dr. Crawford then asked out her boyfriend Kraven the Hunter to find Man Spider, who also tangled with Punisher. Punisher was eventually captured by Man Spider and taken to the World Trade Center parking garage. Kraven followed the mutated hero there and was able to administer another cure, this time reversing the effects. The nightmare was not over however. Spider-Man would have to continually see Dr. Curt Connors to stop the mutation, sometimes the arms would begin to grow again.
Peter continued to deal with the mutation and had to use the Neogenic Recombinator to stop it. Eventually,Vulture used his youth-stealing technology on Spider-Man and accidentally got contracted the problem. Vulture began to mutate and sought out Curt Connors and Farley Stillwell. The two restored Spider-Man's youth but left the mutation in Vulture.
Somehow, Vulture seemed to cure himself of the Man Spider mutation but then faced problems where he constantly changed his age.
When Spider-Man went to Counter-Earth, the Knights of Wundagore used Beastial technology to turn Spider-Man into Man Spider again. He was cured right away.
Another version has just gotten to the point where he grew the extra arms. But instead of seeing them as a bother, this Spider-Man adapted and made a costume to cover the extra arms and got additional web shooters. When he went to fight Spider-Carnage he mutated into Man Spider and attacked the other Spider-Men, which forced the Beyonder to teleport him away.