Carnage is the fusion of a symbiote and the human psychopath Cletus Kasady He currently works for Dormammu.
Limbo
Carnage first appeared during the brief epilogue segment of the final round of Disney Vs Marvel Villains Part One. Upon the creation of Feral Mickey (a combination of Mickey Mouse and Chernabog) he appears and introduces himself as Carnage.
Vs Negaduck
Later on, after spinning around the multiverse for three months, Negaduck found himself in limbo, where he took note of Feral Mickey and Carnage, who have learned to get along over the three months since Feral Mickey's arrival. Negaduck challenges Carnage, who is always up for a brawl. However, this was a grave mistake on Negaduck's part, as Carnage not only destroys Negaduck's gun, but manages to defeat Negaduck by firing a blade that chopped up one of Negaduck's bombs, detonating it and killing Negaduck. Immediately after, Dormammu introduces himself as Carnage and Feral Mickey's new master, taking on a new form.
Spider-Carnage
Madame Medusa and Doctor Octopus begin testing Hob Goblin's old dimensional portal, however, in a freak accident, Spider-Man and Carnage are twirled into the portal, Feral Mickey following them. Carnage and spider-Man's genes splice, fusing the two beings and creating the monstrous Spider-Carnage. This monstrosity scares away Medusa, making Spider-Carnage the new kingpin of crime.