Activists
People who believe in a cause to the point where they take action in order to forward their ends. (e.g. India-Nuclear-Weapons-Protesters) (e.g., X-Ploit) (e.g., NY-Times-Protest) (e.g., Swedish-Political-Activists) (e.g., Bronc-Buster)
Complexity: These people can be extremely zealous - even when they are misdirected. They often consider one viewpoint to the exclusion of all others, try to maximize harm to their victim without regard to competitive issues or personal gains, and typically use physical means - sometimes with the additional element of publicity as part of their motive.