ROMaster2 said: Why does she have a face? There's supposed to be nothing at all.
Each individual Assassin is based off a separate individual, maybe Fate/Zero Assassins have a face because they are all separate while True Assassin in Fate Stay Night HF has no face because he's an agglomeration of all of them.
Then again, maybe they just have faces in this picture because people.
Well, there are 19 Hassan leaders. The one in Fate/Zero was "The Hundred-Face Hassan" who often changed his personality and disguised himself as men, women and even children. It's also noted that he may be the original Hassan who self-inflicted a personality disorder and fragmented himself into eighty to a hundred different entities, each embodying a skill he had learned in his lifetime.
The ones that become leaders are stripped of their original identities to make it seem as if the first Hassan had never died and lived throughout the centuries.
To top that off, it's an organization of assassins, not just one trained at a time. So you can pretty much choose which theory you like to believe in for why there are so many.