The show Supernatural first aired on September 13th, 2005. During its first season, the show received generally mixed critical reception, but reception from critics has grown more favorable as the series progressed with subsequent seasons receiving generally positive reviews from critics. The series originally focuses primarily on the brothers Dean Winchester and Sam Winchester, played by Jensen Ackles and Jared Padalecki, as they travel throughout the country hunting down evil supernatural creatures.
Over the years the series has evolved from hunting down urban legends on the road, to fighting the apocalypse with demons and angels. The Angels storyline added in Castiel, a seraph who eventually becomes the best friend of the Winchester brothers. Originally a short-term role which became a series regular later on. Castiel is played by Misha Collins. He was promoted to a series regular for the fifth and sixth season, something Collins believes to be mainly due to fan support. Collins was downgraded to recurring status for the seventh and eighth seasons, but returned to series regular status for seasons nine and ten
Almost a year later, Season 5 introduces the demon Crowley, played by Mark Sheppard, who would become the Winchester's longest-recurring antagonist and occasional anti-hero in the series. Crowley would alternate between the villain and an ally to the Winchesters. His mother Rowena is also introduced in Season 10, play by Ruth Connell and she experiences the same character development as villain and ally as Crowley does. Eventually, Crowley sacrificed himself fighting against Lucifer at the end of Season 12.
Season 12 also reintroduces Mary Winchester, the mother of Dean and Sam. She is played by Samantha Smith in all but two episodes. She is brought back to life by the villain, turned neutral ally of season 11, Amara. Mary struggles to adapt to the world that has changed greatly from what she once knew and the changes in her sons.
Jack Kline introduced at the end of season 12 is played by Alexander Calvert. He is a Nephilim and the son of Lucifer. Jack was taken in by Sam Winchester and Dean Winchester who would teach him how to master his powers. He eventually kills Michael, an alternate world archangel. Jack begins to damage his soul as he uses his powers after a confrontation with Lucifer, which results in him killing Mary by accident. His attempt to bring Mary back to life only restores her body, and when Castiel goes to Heaven to retrieve her soul, he learns that she has been reunited with John Winchester in Heaven, prompting Castiel to let Mary stay dead so she can be with him.
The end of season 14 begins an intense arch to end the series. Mary has been killed, God shows up once more and when the Winchesters don’t do as he wants, Jack is smote by God. A number of villains and the monster of the week from times past are resurrected.
Dean, Sam, Castiel and Rowena are fighting to keep the world in one piece as season 15 begins.