Maverick

Maverick (イレギュラー) is a term gived to Reploids and Mechaniloids that are a threat to humans, which can be caused by errors, viruses, reprogramming, or even by their own free will upon deciding that humans are too weak to live. They are usually countered by application of superior firepower to a fatal degree, and the Maverick Hunters were formed to enact this.

Mega Man X series
Originally, the term Maverick is used for a Reploid that goes berserk, violent, and insane, normally due to being infected by the Sigma Virus or other type of virus. They were the only enemies that would be in the levels.

Mega Man X4 brought the most attention to the exisistance of non-infected Reploids when the Repliforce are branded Mavericks in their attempts to gain independence from humanity.

In Mega Man X8, it's revealed by Lumine that the Reploids can become Maverick at will, without the need of being forced by viruses or other means.

Mega Man Zero series
In the Mega Man Zero series, the term Maverick is used for any Reploid who opposes Neo Arcadia. Ciel created a Resistance to protect innocent Reploids labelled as Mavericks.

In Mega Man Zero 4, Dr. Weil takes control of Neo Arcadia after Copy X's death, and any who opposes him, human or Reploid, is considered a Maverick. This ended with Dr. Weil's death. Another example of Maverick at will is Elpizo from Mega Man Zero 2, who wants to destroy Neo Arcadia and all human beings for the good of the Reploids.

Mega Man ZX series
In the Mega Man ZX series, there are still Maverick attacks.