Berserker

The opposite of Champion, the Berserker reputation deals with the darker side of morality. Receiving this perk makes dealing with those of less than stellar reputations a little easier.

''You have killed a large number of people. This is generally not a good thing to get known for. People from the wrong side of the track will like you a little more, however.''

Fallout d20
The cancelled Fallout d20 PnP RPG included a berserker advanced character class available to super mutants.