Jeffrey's Demon

Jeffrey's Demon is the overarching antagonist of the Supernatural dark fantasy episode "Repo Man."

His Evil Ranking[]

As part of his hobby he presumably has done before, he possesses Jeffrey and has him murder multiple women, which not only makes him responsible for serial murder but influenced Jeffrey to become a serial killer as he was always afraid to act beforehand.
He murdered a certain amount of women and is seen having killed a woman in the flashback scene and taunted Nora, Sam and Dean about being unable to save her.
He also makes multiple sexist comments to Nora like saying he smells menopause and wanting to "scoop her out like a pumpkin" to psychologically attack her.
He has Jeffrey murder 3 innocent women and his own puppy, as well as trying to lure and murder the Winchester brothers to summon him again.
After summoning again, instead of possessing Jeffrey, who actually wanted to be possessed, he possesses Nora's son.
He planned to burn Nora's son's body, saying "it" didn't have much potential to become a serial killer.
He attempts to kill Sam and Dean.
He psychologically torments Nora before he is exorcised.
He planned to corrupt multiple people into becoming serial killers, even describing it as "creating a new generation of scouts."

Although his hobby of corrupting young psychopaths into serial killers is somewhat unique, he relies on Fridge Horror as his only known victim of this is Jeffrey. Due to the massively high heinous standard of Supernatural, he fails to stand out compared to multiple other characters who've done much worse, such as the Disaster Demon who crashed planes and killed thousands of people, while the rest of his crimes are standard for a Demon. It is also worth noting Lucifer is responsible for corrupting his vessel Nick into becoming a serial killer (albeit indirectly).