Katniss! ♥
Mockingjay.net also has some other pics up of the main tributes and what looks like Effie, Haymitch, and Peeta on the train, but the Katniss one is the one that tugs at me most. It's the closest I've yet seen JL come to embodying my mental picture of the character - hard, vulnerable, young.
Seriously need to dig up some more THG icons.