I mean, I've added several individual pictures, so does that count?
It's nigh impossible to find a single picture that would sum Kat up. 
Because A: she's a woman who doesn't dress so her breasts are popping out.
B: She's black. Really, I made Kat dark skinned because I was tired of everyone being white in SF&F fiction
C: She's a black woman and she doesn't have cornrows or dreadlocks or a mohawk. The one's who pass the first 2 tests always have cornrows or dreads or a mohawk. And while that's all really cool, thats not exactly what I imagine Kat as looking like. 

I've looked for a picture for you guys, and I can't find a single image that sums up what I imagine Kat to look like. I'm sorry, is my series of composite images okay?