I need a good ハロウィン costume for a 13 年 old girl?

Depends what your going for, Classic, new.Im going as Bellatrix Lestrange from Harry Potter

/checks your profile

Hmm, あなた obviously like Percy Jackson, so why don't あなた go as Annabeth? :D They have camp half-blood shirts... And if あなた can't find one they seem easy enough to make.

its always fun to be a princess agasin maybe spice it up going vamp princess または maybe put ears and a tail too:)or maybe medusa または chiron i 愛 greek mythology pick your fav. character:)

Use a Vampire costume

be a cute fairy with big wings

if u like the hunger games go as katniss. if not just wear a plain 上, ページのトップへ with costume written on it!;-)

OHMIGAWD, darling, あなた would look FABOO in this!!! :D

Witch costume,or demon costume...MAKE YOUR CHOISE!!! :DD

try cosplay 4 アニメ like lucky star

Well, I went as a witch when I was 13.