Extremists (a.k.a. Dark Heroes in foreign subcultures) are anti-heroes who undertake extreme means - such as using weapons of mass destruction, torture, mass killings, etc. to stop a villain's scheme - in pursuit of their heroic goals. Many of them tend to straddle the line between good and evil, with some going so far as to fall to the dark side.

These heroes are the good counterparts to villainous extremists.

NOTE: Extremists are not Pure Good as they can commit unpredictable and terrible acts in the name of good, even if they are primarily focused on a revolution or a social change that is noble and meant to benefit society.