With the Nuka-World DLC for Fallout 4, you can meet the violent Porter Gage. Such a tendency for killing comes with the raider territory as he's second-in-command of the Nuka-World Raiders.

Bethesda may have introduced romance in Skyrim by letting you marry a not-insignificant number of NPCs, but Fallout 4 took that ball ... It turns out that a ruthless raider with a history of ...