There is an important pair of fraternal twins. Possibly minor dieties, sorcerers, or maybe just an important pair of nobles. One is evil and one is good. The thing is, the one who looks evil at first glance is the good one, and vice versa.
There is a person who has a well-known reputation, probably involving something illegal. But this person is either very clever and crafty, or really like his or her privacy, for no one knows who this person actually is. As an added twist, perhaps this person is of an age that would noramlly be wildly inappropriate (say, a child is a much-feared bandit) or maybe not the expected gender or even race.
One of the most wanted assassins in the realm looks exactly like an important person (local nobility, PC, etc.) This may or may not be common knowledge.
A certain type of demon cannot not be hit by ranged weapons or attacks. Attacks have to be made up close and personal for the damage to mean something. Ranged attacks are to impersonal.
Possibally a way to make the ranged attacks more meaningful would be to coat the arrow head or what not with the shooters blood. Of course, they'd better be a good shot, otherwise they're wasting arrows and already bleeding to boot.
Spells: wizards might have half or no effect, preist might work due to divine intention.