Season one - The first season of Supernatural, an American dark fantasy television series created by Eric Kripke, premiered on September 13, 2005, and concluded on May 4, 2006, after 22 episodes. It focuses on brothers Sam and Dean Winchester as they track down their father, John, who is on the trail of the demon who killed their mother and Sam's girlfriend. During their travels, they use their father's journal to help them carry on the family business—saving people and hunting supernatural creatures. 
 
Season two - The second season of Supernatural, an American dark fantasy television series created by Eric Kripke, premiered on September 28, 2006, and concluded on May 17, 2007, airing 22 episodes. The season focuses on protagonists Sam (Jared Padalecki) and Dean Winchester (Jensen Ackles) as they track down Azazel, the demon responsible for the deaths of their mother Mary and father John. They attempt to discover the demon's plan for Sam and other psychic children—young adults who were visited by Azazel as infants and given abilities, and whose mothers often then died in a fire. During their travels, they use their father's journal to help them carry on the family business—saving people and hunting supernatural creatures.
 
Season three - The third season of Supernatural, an American dark fantasy television series created by Eric Kripke, premiered on October 4, 2007, and concluded on May 15, 2008. Traveling throughout America, protagonists Sam (Jared Padalecki) and Dean Winchester (Jensen Ackles) use their father's journal to help them carry on the family business—saving people and hunting supernatural creatures. The season begins with the brothers tracking down the demons released from Hell in the previous season finale. They become allies with a demon named Ruby (Katie Cassidy), who claims to know a way to release Dean from his demonic pact—he had sold his soul to a demon and was given a year to live in exchange for Sam's resurrection—and wants to protect them from the new demonic leader Lilith. As Dean's deadline approaches, their efforts are further hindered by Bela Talbot (Lauren Cohan), a professional thief of occult items who is often at odds with the Winchesters.