A Madboy is a Feral Ork who has developed a psychosis after his introduction to advanced forms of technology. The ancient xenos known as the Old Ones, called by the Orks "Brain Boyz," created the Krork, the predecessors of current Orks, who may have been created to serve as a form of biological weapon in the Old Ones' long war with the Necrons. The Old Ones essentially "hardwired" all of the technological knowledge they deemed necessary into the Krork's genetic structure, from which it passed down to the Orks, a species that reproduces asexually through the use of spores that are periodically given off by every Greenskin. However, not all of the inborn knowledge of an Ork is immediately available. When Orks are "born" on a world where advanced technology does not exist, they will possess technical knowledge equivalent to that of humans during the Old Stone Age. Orks will slowly unlock the remaining knowledge of advanced technology naturally over the course of several generations of Greenskins, ending with the instinctive ability of Greenskin Mekboyz to build functional gravitic technologies like Warp-Drives, tractor beams and force fields which will allow them to migrate across the stars. Primitive Orks who have not yet attained the advanced technology required to cross interstellar distances are known as Feral Orks. To these Orks, introduction to even moderately advanced mechanical devices can prove to be mentally overwhelming, as the instinctive technical knowledge buried within their genes activates instantaneously instead of over time.
Those Orks that cannot bear the sudden mental strain of exposure to advanced technology are collectively known as "Madboyz" or "Nutters" by their fellows and are usually grouped together in squads that can prove to be either a secret weapon for an Ork force or a deadly hindrance. As a result of their psychosis, even other Orks will be careful to keep their distance from a Madboy. Once combat erupts, Madboyz can prove to be savage fighters or can suddenly be overwhelmed by their insanity and start attacking other Orks, argue over whether a particular tree looks like Gork or Mork, or huddle in a gibbering panic. With a Madboy, other Greenskins never know exactly how they will behave, which represents both the peril of these insane Orks -- and the possibilities.
- Chapter Approved 2003, pp. 4-10
- Codex: Orks (4th Edition), p. 37