Female and generally envisioned as reasonably young (late teens to early thirties)
First (given) or last (family) name begins with "K" (or, if from a different language with different alphabet, would be transcribed to the English alphabet as a K)
Reasonably describable as an "Action Girl" within the context of their origin. Appropriate characters who unfortunately don't fit the "K" criterion would be Elizabeth Turner from the Pirates of the Caribbean, Xena, Jean Grey/Phoenix, Red Sonja, Calleigh DuQuesne from CSI: Miami, etc.
They must be iconic/important enough in their source material to be reasonably likely to draw the attention of fans rather than be a "oh, yes, she was in there too" kind of thing.
Preferably redheaded, or if the source material varies, COULD be redheaded without damaging the character concept (some concepts rely on the physical appearance echoing some other concept).
I have my own set of candidates, but I'm interested to see how many come up in a wider context.
EDIT: I'm surprised by the paucity of candidates so far. At this point I've seen only two or three candidates, both here AND on Usenet where I also posted this question, who weren't already on my list.