Assamite

There’s something sad and about having a vampire clan full of nothing but badass assassins, but damned if the Assamite don’t manage to be kind of awesome anyways.

First of all, they’re not just assassins; they also include sorcerer and Viziers (scholars of a sort), all with their own specific powers. Despite happily taking contracts as hitmen, they aren’t evil and they don’t get involved in all the nonsense of the other vampire clans.
Most important, all Assamites have the Discipline of Qietus which, despite its name, allows vampires to control the blood of others, which lets them do awesome things like targets to sweat blood, turn blood acidic, and other craziness. Yes, it may be completely clichéd to be a quiet, noble assassin, but when you can take control of another vampire’s blood from afar, people don’t tend to give you too much grief about it.