10. Walter White (Breaking Bad)
Position: Chemistry Teacher, J.P. Wynne High School/Meth Cook, An Old, Run-Down RV; In the Basement of an Industrial Laundry Business; Abandoned Poison Houses
What he taught us: That it doesn't matter if you're one of the world's leading minds in your professional field. One small misstep, and you'll be in a dead-end job for the rest of your life. As a mythical meth manufacturer, Walt's proteges have gone on to do some pretty impressive things, such as realizing his true, evil nature and trying to kill him, or getting in his way and being shot in the face. Luckily, Walt's seen the error of his ways, and now only instigates the most watertight of plans, on the condition those plans involve as many child deaths as possible.
9. Mr Feeny (Boy Meets World)
Position: Everything Teacher, Everywhere
What he taught us: Mr. Feeny is either the best or worst mentor of all time. Best because he was never very far from Corey, consistently guiding him through life. Worst because, well, that. I suppose every mentor/student relationship can look a little creepy from the outside, but for seven years this guy didn't leave those kids alone for a single goddamn week . The only explanation is that Mr. Feeny is living out some kind of demented fantasy, playing with his teenage victim's impressionable young minds to fulfill his own desires from his empty and wasted youth. That or he just happened to see something of himself in Corey, and took it upon himself to make sure he made the most of his potential, and not make the same mistakes as his mentor. But that seems unlikely.
8. Mr Miyagi (The Karate Kid)
Position: Karate Instructor/Handyman, LA
What he taught us: A bunch of karate, and also that the words "Hey, just a heads-up, I know these jobs all seem pretty menial and useless, but they're installing some seriously kick-ass fighting moves into your subconscious, so hang tight." would probably go a long way. Miyagi's a quiet, gentle, tortured soul, who truly believes in the goodness of humanity and the necessity of non-violence wherever possible, which is lame as fuck, but he's great at punching people's faces in if it comes down to that. So it's fine.
7. Professor Snape (Harry Potter)
Position: Potions Professor/Defense Against The Dark Arts Professor/Headmaster, Hogwarts School of Witchcraft and Wizardry
What he taught us: Snape, more than anyone else, demonstrated the value of commitment to a job. He went above and beyond in his role as a potions professor, since at the same time he was also double-agenting as a member of the most evil wizard alive's posse. Years after his heart was broken by the love of his life and his childhood tormenter, he found himself with the thankless task of protecting their son, being reviled and distrusted by just about everyone he worked with/taught. After being forced to kill the only man who ever believed in him, Snape was brutally murdered by his other boss, and would never know if his life devoted to solitude and secrecy was ever worth it. It all panned out in the end, though, because Harry and his ugly wife named their kid after him.
6. Professor McGonagall (Harry Potter)
Position: Transfiguration Professor, Hogwarts School of Witchcraft and Wizardry
What she taught us: Alongside Downton Abbey, that Maggie Smith in any role is pretty much an irrefutable badass. As enjoyable as the Dowager Countess' count-less (you're welcome, everybody) one-liners are, McGonagall's Scottish sternness and the FACT SHE CAN TURN INTO A CAT WHENEVER SHE WANTS gives her the edge.