Full name: Mary Winchester
Maiden Name: Mary Campbell
Date of birth: December 5, 1954
Date of death: November 2, 1983 (age 29)
Occupation: wife and mother; former hunter
Hometown: Lawrence Kansas
First Appearance: Pilot
Most recent Appearance: The Song Remains The Same
Seasons: 1, 2, 4 & 5
Fate: Killed by the Yellow Eyed Demon
Mary Winchester, portrayed by Samantha Smith and by Amy Gumenick (in time-travel episodes), is the wife of John Winchester and mother of Sam and Dean.
In the pilot episode, it is revealed that, six months after Sam's birth, Mary was awakened by sounds of him crying in his crib. She discovered Azazel there - later revealed
to have been feeding Sam his demonic blood - and confronted him, but was pinned to the ceiling by him and slashed across her abdomen, eventually bursting into flames.
According to series creator Eric Kripke, her relation to Azazel was supposed to be addressed in the third season, but was pushed back to the fourth season due to the
writer's strike.
In the episode "Home", her sons return to their childhood home in Lawrence, Kansas to investigate a recurring dream Sam experiences. Mary's spirit seemed to haunt the house
in Lawrence, Kansas, and a poltergeist was in the house with her, though the psychic Missouri Moseley never felt their presence. After the poltergeist pinned Sam to the
wall, Mary appeared as a fiery figure. When Dean broke through the locked door to reach him, Mary told Sam that she was sorry. Turning to the ceiling, she told the
poltergeist to leave her sons alone. Her spirit fought with and canceled out the poltergeist, forcing both spirits out of the home.
In All Hell Breaks Loose, Part 1, the Demon shows Sam the night Mary was killed because she was in the wrong place at the wrong time. When Mary ran back into the nursery
she said "It's You!" to the Demon. It remains unclear how she could have known the Demon. In Supernatural: Origins, it seems that Mary has a sister that the Demon was
apparently after, but this is unconfirmed.
In "The Kids are Alright", it is revealed that all of Mary's friends and acquaintances have been killed off in the years since her death, although the reasons for this are
never explained.
It is later revealed in the episode In the Beginning that Mary was a former hunter, along side her parents Samuel Campbell (father) and Deanna Campbell (mother).
Dean was sent back in time by Castiel "to stop it" the Yellow Eyed Demon was making deals with people because he wanted the future children, the deal was told to be
that he would return to the people whomever he made deals in ten years. Mary, Samuel and Dean were investigating the scenes of the crimes and Mary was exposed to the
Yellow eyed demon. Later on Dean confesses to his grandfather who he is, but he is already possessed by the demon and he kills both his grandparents. He finds Mary
eventually and kills John. The Yellowed Eyed Demon proposes that he will bring John back to life and she can live a normal life with no demons and with John, on the
condition that he will arrive at there place for something in ten years. Mary reluctantly agrees and the Deal is made, Dean is sent back to the present time with the
understanding and knowledge of how things turned out to be.
Information from Supernatural Fan Wiki.