The most horrific monsters are not alien beings from Doctor Who or whatever but are human beings who look normal but definitely don't act in a normal manner. Normal in terms of acting decently towards other people, whether we agree with them or not.
The monsters take the form of those who think it all right to killl and maim and take hostage in the name of their twisted ideology which does not reflect the majority of people's views (from all backgrounds).
To the good people of Paris, I am so sorry. I hope your ordeal is over soon.