6. Demon: Ruby
If it wasn’t for the demon Ruby, the Winchesters would have been dead. She was the one who revealed crucial information to the Winchesters which helped them in taking down the demons. The demon helped the boys in saving Anna and even helped in restoring the Colt. She even provided them with the demon killing dagger. But later we learned about her ulterior motives, all this time she was working for her selfish purpose and placed Sam Winchester in danger.
7. Angel: Castiel
Undoubtedly, he is the most beloved angel in the Supernatural Universe. It’s interesting to imagine that Castiel was supposed to last only for a few episodes, but his popularity and positive reception convinced the writers to make him a regular character. He played a significant role in most of the storylines and became a close member of the Winchester family. Castiel always tried doing the good, but his naiveness often caused more bad than good.
8. Demon: Cain
The story of Cain and Abel has been told several times. While many people know that Cain killed Abel in a fit of rage. But Supernatural revealed that Cain was only trying to protect his brother and he made a deal with the devil, king of Hell, Lucifer. After killing Abel, he bore the mark which tormented him, he even trained the Knights of Hell on the orders of Lucifer. He had a change of heart when he accidentally ended up killing the love of his life, a woman named Colette.
9. Angel: Lucifer
He is pure evil and selfish, but totally entertaining. Lucifer’s motivations changed from time to time, but one thing was constant, total chaos. He was the big bad villain of Season 5. He kept making appearances throughout the 15 Seasons. There have been numerous versions of Lucifer in TV and movies history, but Mark’s Lucifer is totally ruthless and one of a kind.
10. Demon: Dean
In Season 9 finale, Dean died at the hands of Metatron, but the mark of Cain wouldn’t let him die. He awoke from the dead, but he returned as a demon. Demon Dean lasted only for a short time, but it was totally fun. He didn’t care about anyone, he challenged the authority of Crowley, even tried killing Sammy. Ultimately, Sam with the help of Castiel was able to cure the demon Dean.