1. Luna Lovegood
On a scale of 1 to dead as soon as zombies strike, I'd rate Luna a 9. She's fierce but flighty and she'd get lost from a group of survivors easily. She'd be dead inside a week.
2. Alina StarkovAlina is pretty bad ass. I think she would survive a long time - at least a year, probably longer.
3. Fred WeasleyGeorge, wonderful and talented as he is, would probably meet the same fate as his twin soon. I give him the same time span as Fred.
4. George Weasley
Fred is pretty awesome with the pranks and the Weasely's Wizard Wheezes. HOWEVER, I think that Fred would be bitten off fairly quickly. I'd give him 4 to 6 months.
5. Kaz BrekkerKaz is bad ass. I mean?!??! However, I think his mobility issues would make it hard for him to hide from zombies for too long.
Tris is bad ass. I mean - she left her parents and joined Dauntless in her choosing ceremony, hid her divergence for how long, and did so much more! I give her a year, maybe longer.
7. Hermione GrangerThe beaded bag, the punching Draco Malfoy in the face, all the help she gave her friends over the years. She'd be one of the last two die. I'd give her at least 2 years - but probably more.
8. Katniss EverdeenIt's Katniss! She survived 2 hunger games, killed President Coin and put up with all sorts of stuff from Haymitch and everybody else. She's going to be the last survivor. Every other person in the world will die before Katniss.