Zombies, also known as zeds, are people in the Madness Combat world who have died and reanimated by Jesus. The only zombies not to be revived by Jesus is Tricky, who was revived thanks to the Sheriff activating the Improbability Drive, and the zombies in Madness: Project Nexus, who were revived as a result of Project Nexus. In Project Nexus, if someone gets killed by a zombie, he will be revived as one.
Zombies appear in Episode 1.5 of the Story Mode. Dr. Christoff releases them during his rebellion against the project. At first, the zombies attacked Dr. Christoff, agents, riot guards and scientists indiscriminately. However, in the last level, Phobos regains control over the Nexus and makes the zombies loyal to him, causing them to only attack Dr. Christoff.
Zombies also appear as the enemies of Zombie Arena Mode. There are five types of zombies that can appear: regular zombies, zombie Agents, zombie A.T.P. Engineers, zombie A.T.P. Soldats and zombie G03LMs. Each type has different levels of resistance and aggression.