Yeah, I'm one of those fangirls. At least I'm becoming one.
Supernatural started in 2005 and right now there are nine seasons. I'm on the third season. Each episode is around 45 minutes and I think there are around 22-23 episodes in a season.
The show focuses on two brothers, Sam and Dean Winchester. After the tragic death of their mother many years ago, their father goes on a quest to hunt down the demon who killed her. Their childhoods caused them to be trained like monster hunters.
They pick up where their father left off, traveling around the country and fighting all different kinds of monsters.
It's a really scary show sometimes and I wouldn't recommend it to the lighthearted or really young kids, but the characters are lovable and each plot behind the monsters is really thrilling.