The Nanaya clan in Tsukihime. A family of assassins. Seclusive, described as vicious killers and also seem to have a penchant for rape. The only glimpse we get of one is Nanaya Shiki, the hero's Super-Powered Evil Side who first brutally destroys Arcueid and then later tries to rape her. However, as Akiha points out, they weren't actually that bad (nor that were they very good either) because the only ones they ever had that impulse towards were non humans, who generally are not good people to have around (i.e. the Dead Apostles, demons and the inverted members of the Tohno family). They still seem to enjoy themselves a little too much when 'working' though.
Actually, the rape was due to Arcueid's mystic eyes. It had absolutely nothing to do with the Nanaya side.
Why aren't we regarding Arcueid herself as this? She's a vampire, after all.