The Extremist is a 4-issue miniseries published by DC/ Vertigo in the early 90's. It has never been collected in one book. The series was helmed by writer Peter Milligan and artist Ted McKeever, and it is somewhat of a career high point for both of them.
This series tells the story of 'The Extremist'; the strong-arm law enforcement for a secret society of high society sexual deviants. The story is told in a wonderously non-linear fashion with each issue being told from the perspective of a different character.
This mini series was collected as: Vertigo Resurrected: The Extremist