Season 9 sees Sam and Dean facing off against a new enemy: the Darkness. The season also explores the show's mythology, including the introduction of the Nephilim.

Season 3 marks a significant turning point in the series, as Sam and Dean face off against Lucifer, the fallen angel. The season introduces new characters, including Castiel (Misha Collins), an angel who becomes a key player in the show.

The twelfth season continues the story of Sam and Dean as they deal with the aftermath of the Apocalypse. The season introduces new characters, including Ash (DeAnna Pappas) and Mahindra (Rohan Chand).

The eighth season continues the story of Sam and Dean as they deal with the aftermath of the Apocalypse. The season introduces new characters, including Gadreel (David Harvey) and Metatron (Dean Stockwell).

Season 7 sees Sam and Dean facing off against a new enemy: the Reapers. The season also explores the show's mythology, including the introduction of the Men of Letters.

In this article, we will take a comprehensive look at all 15 seasons of Supernatural, highlighting key episodes, characters, and storylines. Whether you're a die-hard fan or a newcomer to the series, this guide will provide you with a thorough understanding of the show's evolution and its enduring appeal.