Do wars count? I find it strange, to say the least, that humans have strong feelings about singling out an individual for violence but give relatively little thought to dropping bombs on hundreds or thousands of nameless, faceless humans.

Context matters, and trying to describe an ethical situation in enough detail to arrive at a meaningful answer may indirectly identify the participants. Should there at least be an exception for notorious people or groups who happen to still be living instead of relegated to historical "bad guys" who are almost universally accepted to be worth killing? I can think of numerous examples, living and dead, who were or are the target of state-sponsored violence, some with fairly good reason.