The Crimson Head (クリムゾンヘッド,kurimuzon-heddo?) is one possible mutation a zombie can experience, depending on the strain of t-Virus it is infected with. The V-ACT process is responsible for its crimson skin, earning it its name.
Crimson Heads were the result of the unforeseen effects of the ε strain on the human body. The strain, developed for the Tyrant Project, was released in the Arklay Laboratory during a lab accident. As the facility's staff had no experience with Crimson Heads aside from the brief, violent encounter with Crimson Head Prototype 1, they were at a disadvantage, and an informal policy became to destroy the bodies of Zombies to prevent further mutation.