Season 4, Episode 13
After School Special
Sam: I'm not evil, Dirk. I'm not. And neither were you. Trust me. I've seen real evil. We were scared and miserable, and we took it out on each other — us and everybody else. That's high school. But you suffer through that, and it gets better. I'm just sorry you didn't get a chance to see that... you or Barry.
Sam and Dean discover that a spirit is haunting one of their old high schools. While investigating the haunting Dean and Sam relive their high school experiences through flashbacks recalling how Sam was picked on by the school bully while Dean was Mr. Popular. They discover that the spirit was a former classmate of Sam's who he thought was a bully. In reality, it was the bully who had been tormented by jocks and has come back to seek revenge on those who pick on the nerds.
For this episode = 1 human and 1 ghost.
For the series so far = At least 284 humans (of which 5 were witches), at least 61 demons, 26 ghosts, 10 vampires, 6 changelings, 3 gods, 3 shapeshifters, 3 zombies, 2 werewolves, 1 cat, 1 crocotta, 1 djinn, 1 dog, 1 rakshasa, 1 rawhead, 1 rougarou, 1 shtriga, and 1 wendigo.