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.
The zombies only appeared in episodes 1-5, where in each of these episodes, they are revived by Jesus to take down Hank at all costs. However, despite their superior numbers and strength, Hank is able to take the zombies out easily before engaging into a fight with Jesus. However, the only zombie that Hank has trouble killing is Tricky, who has gotten himself an Improbability Drive that allows him supernatural powers that surpass those of other zombies.
Eventually, in episode 7, Jesus destroys the Drive, which deprives Tricky of his power before being killed by Jesus, making him the last zombie to die in the series.
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.