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.

The show gained mostly positive reviews, with the cast and crew garnering many award nominations and praise being given towards the brotherly chemistry between the two leads, however the formulaic structure of the episodes was criticized.

[12] Adrianne Palicki reprised her role as Sam's deceased girlfriend Jessica in the alternate-reality episode "What Is and What Should Never Be", as did Samantha Smith as Mary Winchester.

[14] However, the character dies in the premiere because the writers worried that having him separated from his sons again—Sam and Dean spend much of the first season tracking him down—would "split the show" by having him away "doing more interesting things than the boys are doing".

The reins passed to Fredric Lehne for the second-season premiere, and the show's producers enjoyed his performance so much they brought him back for the two-part finale.

Though a fan of the show, Blair had turned down a guest appearance in the first season because she did not want to return to horror, having spent years getting a "clean slate".

"[49] The casting of Battlestar Galactica's Tricia Helfer in "Roadkill" stemmed from the producers' preference to hire actors important to Supernatural's fanbase.

[50] Kripke enjoyed Emmanuelle Vaugier's work in television series such as Smallville, and believed she was an "easy choice" for the large role of the soon-to-be werewolf Madison in "Heart".

Director Kim Manners felt Vaugier brought to the character a vulnerability like that of Lon Chaney Jr. in The Wolf Man, which made viewers sympathetic.

[51] Conspiracy-theorist Ronald of "Nightshifters" was envisioned by writer and consulting producer Ben Edlund as the unsympathetic "semi-drunk Randy Quaid from Independence Day".

[52] The producers considered Summer Glau for the role of the zombie Angela for "Children Shouldn't Play with Dead Things", but she could not accept due to scheduling conflicts.

"[54] This change brought the series' focus onto situations such as the brothers dealing with their father's death and giving them the task of hunting down Azazel, the demon who killed him.

To circumvent this, writer Sera Gamble suggested Johnson's story be made into a subplot detailed in flashbacks, with the Crossroads Demon returning in the present to make more deals.

One of the writers' first creative ideas of the season was depicted in the teaser of "Born Under a Bad Sign", in which a blood-covered Sam wakes up not remembering the past week of his life.

[19] Writer John Shiban suggested that the brothers be arrested on purpose in order to work a job, with the prison's head guard being revealed as a family friend.

For his scenes as the yellow-eyed demon Azazel throughout the season, Fredric Lehne wore hard, colored contact lenses that greatly obscured his vision.

Wanek noted, "They were in this really odd-looking motel that had crystal chandeliers and carved beds, turquoise stove and refrigerator, and this wonderful period linoleum on the floor.

[84] The final scenes of "Simon Said" were filmed at Cleveland Dam,[72] and "All Hell Breaks Loose, Part One" made use of a pre-existing set built for the Western television series Bordertown.

For "Simon Said"—featuring characters with the ability of mind-control—Gruska tried to make the score more "mind-trippy", opting to mainly use "synthy, spacey electronica pads" to give it a science-fiction sound.

[93] Lennertz used organ, drums, bass, and guitar to have a "retro bluesy approach" for "Folsom Prison Blues", mimicking the style of film composer David Holmes.

Cockroaches were digitally inserted into the sewer scenes of "No Exit"; director Kim Manners did not ask for it, but thought the addition "made it really creepy".

The department added blood flowing from underneath him, and also made his fingers twitch and his mouth open and close to create a more lifelike appearance.

[100] To depict a woman burning to death in the episode "Simon Said", the actress was sealed inside a full body silicone designed to look like her, and was doused with fire accelerant.

[91] Prior to "Heart", Kripke had not wanted to include werewolves in the series, as he felt that the budget would only allow for "a guy with fur glued to his face".

[101] As he prefers to have monsters be able to walk among humans, production made the transformation subtle—the character's eyes change, and her canine teeth and fingernails grow.

While at first hesitant of the series, believing it to be "another horror/sci-fi/occult hybrid currently igniting ratings", he found the "eerie and intricate storylines" to overcome the "initial impressions of Clearasil ads and Paris Hilton in House of Wax".

Praising the cliffhangers and the brotherly chemistry between the lead actors, Kaz deemed Supernatural "one-helluva edge-of-your-seat, ball-burner of a series with a forceful script, excellent acting (said pretty boys included) and some fine special effects".

Regarding Sam and Dean, she noted the series' "ability to hone in on [sic] the brotherly conflicts and emotions threaded through a well-plotted monster-of-the-week story".