"The Magnificent Seven" (Season 3, episode 1) is monumental for the first inclusion of a blade that can kill demons as well as the person that wields it. Ruby makes an impressive debut before going on to become a major player (in several different meat suits) over the course of the show.

Jack is not the first Nephilim to be featured on "Supernatural". In season 8, Castiel kills the Nephilim Jane in order to help Metatron close the gates of Heaven.

Castiel, drunk on Purgatory souls, destroys Raphael but allows Crowley to escape. Feeling unstoppable, he declares himself the new God.

In "Holy Terror" (Season 9, episode 9), everyone's favorite prophet, Kevin, dies at tht hands of Gadreel who has been posing as Ezekiel inside Sam's body.

In "Just My Imagination" (Season 11, episode 8), Sully, Sam's imaginary friend from his childhood, pops up to ask the Winchesters for help because someone is out there killing imaginary friends.

Series creator Eric Kripke originally intended for the brothers' last name to be "Harrison" as a nod to actor Harrison Ford, because he wanted Dean to have the "devil-may-care swagger of Han Solo". However, there was a Sam Harrison living in Kansas, so the name was changed for legal reasons.

As the first Reaper to die after Dean killed the old Death, Billie got a promotion.

Season 1 ends on a cliffhanger when a car accident severely injures all three Winchesters.