red hair guy(s)

Kurama from Yu Yu Hakusho

Rin Matsuoka from Free!
Kenshin Himura from Rurouni Kenshin
Gaara from Naruto
Gene Starwind from Outlaw Star
Noba from Bleach

Karma from Assassination Classroom (Pic, one on the left)
Shirou from Fate/Stay Night UBW
Kouha, Koumei, and Kouen from Magi the Kingdom of Magic

That was harder than it should have been... Anywho, Misaki Yata from K~

kagami taiga and akashi from Kuroko no Basket amor this show

Bunta Marui (pic)
Eiji Kikumaru
Gakuto Mukahi
Kintarou Tooyama

All from Prince of tenis :3

Adlet Mayer
Luke fon Fabre

Shanks (One Piece)

SHANKS IN HIS TEENAGE..!!!!!!!!!!!

ittoki <3
prince sama

Ayato Sakamaki from Diabolik Lovers

His hair is actually reddish-brown... (hope its acceptable)

Akashi Seijuuro - Kuroko no Basuke
Ayato Sakamaki - Diabolik Lovers
Gaara - Naruto
Sora - No Game No Life

Hmm..Pod(Chili) from the Pokemon Best Wishes series has red hair!

cuervo from mostrar por Rock (image),
there are also :
-Renji Abarai from Bleach (don't know if I can call him a teen though, but he's hot)

-Yusuke Asahina from Brothers Conflict)

-Rin Matsuoka from Free Iwatobi Swim Club and Free Eternal Summer

-Lavi the Bookman from D Gray Man

-Gaara of the sand from naruto and naruto Shippuden

-Grell Suitcliff from Black Butler (don't know if we can call him a teen either but damn)

-Ayato and Raito Sakamaki from Diabolik Lovers

-Karma Akabane from Assassination Classroom (he is much younger then the others)

-Akashi Seijuro and Kagami Taiga from Kuroko no Basuke

-Masrur from Magi The Labyrinth of Magic (he's a man, but damn, he's hot)

Hope this Helps, and Good Luck ^^

Mikoshiba Mikorin (Gekkan Shoujo Nozaki-kun)

-Akashi seijuro
-Kagami taiga(though he has a little mix of black hair)
-Gaara
-matsuoka rin
-Senri Shiki(not sure if he's red haired)

2p America/Allen from 2pTalia (dont have a picture of him bc i did not feel like it ^w^)