1 Izaya Orihara - Durarara!!
This one may require an explanation... He conducts living experiments and pressures you to respond to the results. He is inadvertently a mentor for everyone he analyzes, for all of them experience something new. - Wopwop
2 Master Roshi - Dragonball Z
Master Roshi is an anime fictional character from the anime series, Dragon Ball Z, created by Akira Toriyama.
3 Eikichi Onizuka - Great Teacher Onizuka
How is it not Eikichi Onizuka? The only people who think Eikichi Onizuka is not the best anime mentor of all time are people who have never seen GTO. He's got the best education philosophies and methods and will stop at nothing to protect his students.
4 Kakashi - Naruto
Kakashi Hatake is a fictional character in the Naruto manga and anime series created by Masashi Kishimoto.
5 Haku - Spirited Away
6 Shanks - One Piece
''Red-Haired" Shanks is a fictional character in the One Piece franchise created by Eiichiro Oda. He is the captain of Red Hair Pirates and member of Yonko. He is also a former member of the legendary Roger Pirates, the only group to successfully conquer the Grand Line.
7 Kamina - Gurren Lagann
Kamina is a fictional character in the anime series Gurren Lagann, known in Japan as Tengen Toppa Gurren Lagann, animated by Gainax and co-produced by Aniplex and Konami. It was also directed by Hiroyuki Imaishi and written by veteran playwright Kazuki Nakashima.
"Don't be distracted by the what-if's, should-have's, and if-only's. The one thing you choose for yourself - that is the truth of your universe." - Kamina from Tengen Toppa Gurren Lagann - ModernSpongeBobSucks
Too bad, he died. :'(
8 Ryuk - Death Note
Ryuk is a fictional character in the manga series Death Note, created by Tsugumi Ohba and Takeshi Obata.
9 Grandpa Solomon - Yu-Gi-Oh
10 Professor Oak - Pokemon
11 Jiraiya - Naruto Shippuden
12 Yoshida Shouyou - Gintama
Shouyou was the master of Gintoki, Katsura, and Takasugi.
13 Arataka Reigen - Mob Psycho 100
14 Genkai - Yu Yu Hakusho
15 Kaede - InuYasha
16 Izumi Curtis - Full Metal Alchemist
Izumi Curtis is a fictional character from the Fullmetal Alchemist manga series and its adaptations created by Hiromu Arakawa.
17 All Might - My Hero Academia
18 Yuuno Scrya - Magical Girl Lyrical Nanoha