Real Name: Ruby
Date of Death: 1350's (went to hell and became a demon over time)
Location: No fixed address
Occupation: Witch (formerly), Demon (currently)
Actresses: Katie Cassidy (Season 3), Genevieve Cortese (Season 4)
Episodes: 3.01 The Magnificent Seven, 3.02 The Kids Are Alright, 3.04 Sin City, 3.09 Malleus Maleficarum, 3.12 Jus in Bello, 3.16 No Rest For the Wicked, 4.01 Lazarus Rising, 4.02 Are You There, God? It's Me, Dean Winchester, 4.03 In the Beginning, 4.04 Metamorphosis, 4.09 I Know What You Did Last Summer, 4.10 Heaven and Hell, 4.16 On the Head of a Pin, 4.20 The Rapture, 4.21 When the Levee Breaks, 4.22 Lucifer Rising
As Sam is attacked, the mysterious woman who had followed him earlier appears, who we will later know as Ruby, and attacks the demons with a knife, which kills two of them, while Sam helps her kill the third. The woman disappears after revealing she knows who Sam is.
3.01 The Magnificent Seven
Ruby first appears following Sam and Bobby as they track down the Seven Deadly Sins. While Bobby and Dean are fighting off Sloth and lust, the others led by Pride go after Sam but are joined by Ruby who gets in on the the fight and attacks the demons with a knife, that appears to be able to kill demons, and kills two of them while Sam helps her kill the third. The woman disappears mysteriously after revealing she knows who Sam is.
3.02 The Kids Are Alright
Ruby meets with Sam unexpectedly as he researches ways to save Dean's soul. She claims she is a hunter, and insinuates things about Sam's past and his destiny, setting him on a path to research more about Mary Winchester. Disturbed to find all of his mother's friends are dead, Sam demands to know exactly who she is. Ruby reveals she is a demon, and claims that Sam fascinates her and, in the pursuit of knowledge for her own ends, is "on his side". The episode ends with her offering Sam a deal - he works with her to find out more about his destiny, she helps him save Dean's soul from the Crossroads Demon.
3.03 Bad Day At Black Rock
Sam tells Dean about his encounter with Ruby, although not about the information she gave him about the deaths of Mary's friends. Dean is angry that Sam didn't kill the demon, while Sam insists that they can use her to get information about the demons they are battling, as well Dean's deal with the Crossroads Demon.
3.04 Sin City
Ruby comes to Bobby while he is working on The Colt. Bobby shoots her with it, but with no effect. Ruby offers to help Bobby make it work, and they succeed - Bobby brings the Colt to a hunt Dean and Sam are on and Sam kills two demons with it. Later, Ruby and Sam argue - Ruby threatens to take the Colt from Sam and give it to someone else who'll use it; Sam threatens Ruby with the Colt. They come to a truce again when Ruby reminds Sam that if he kills her, she can't help him save Dean's soul. She refers to herself as "the little fallen angel' on Sam's shoulder.
3.09 Malleus Maleficarum
Ruby appears to warn Sam and Dean away from the town where they are investigating a coven of witches. She tells them a demon is present that will come after Sam. Dean tries to shoot her with The Colt, but Sam intervenes. When Dean is attacked by a force that causes him to bled internally, Ruby saves him with a witch's potion. When Tammi is about to kill Sam and Dean, Ruby appears and at first acts as if she is on Tammi's side, but then tries to kill Tammi with her knife. Tammi reveals Ruby was once a witch who sold her soul to her. After Dean manges to kill Tammi with Ruby's knife, she tells him all demons were originally human, but during their time in hell they lose all trace of their humanity, but she has retained some of hers and wants to help humans. Ruby reveals to Dean that she can't save him from hell, but that she needs his help to prepare Sam to fight the demons after he is gone.
3.12 Jus In Bello
While the boys are under seige from demons while in a police station, Ruby shows up, able to get in through a salt line damaged unwittingly by the deputy. She tells them that demons are from Lilith, Sam's demonic rival from "the west", and tries to convince Sam that the solution is a spell she knows that will "vaporise" all demons within radius - including herself. However the spell requires the sacrifice of a virgin. Nancy volunteers but Dean is vehemently against the plan, convinced Sam instead that they need to just open the doors and fight off the hoard themselves. Exasperated, Ruby leaves.
After the boys have escaped, seemingly victorious over the demons, Ruby turns up at their motel room & tells them to turn on the television, where they find out that everyone left in th epolice station was killed by Lilith.
3.16 No Rest For the Wicked
In an last attempt to save Dean from his deal, Sam summons Ruby. She tells him that he contains the power necessary to defeat Lilith, but Dean intervenes and in the ensuing struggle traps her beneath a devil's trap and steals Ruby's Knife.
Ruby escapes and tracks the boys to the house where Lilith is tormenting a family. On entering the house they find the little girl Lilith was possessing is human again. Sam turns to Ruby for help again, but she says it is too late to save Dean. As the hellhounds come for Dean, the boys barricade themselves in a room. Dean, who is able to see the true face of demons, realises that the body possessed by Ruby now contains Lilith. Lilith says she has sent Ruby "far, far away".
After Lilith leaves Ruby's body, the latter is seen lying on the floor beside Dean, lifeless.
4.01 Lazarus Rising
Ruby has returned and possessed another body to walk among humans. Since Dean's death, she apparently has taught Sam to use his powers, among them the power to exorcise demons by forcing them out of their host bodies with the sheer power of his will.
4.02 Are You There, God? It's Me, Dean Winchester
Ruby has found out that Dean was saved by an angel. She tells Sam she is going to take off for while because she is scared that angels will smite her, even if she is being helpful to him.
4.03 In the Beginning
At the beginning of the episode, Sam leaves a sleeping Dean and leaves to go somewhere with Ruby.
Dean finds Sam with Ruby, and witnesses him exorcising a demon. Ruby attacks Dean, but Sam warns her off, and she leaves to take the now unpossessed human to hospital.
4.09 I Know What You Did Last Summer
In the present day, Ruby informs Sam and Dean that a woman called Anna Milton is being pursued by demons. She helps save Anna when Alastair attacks.
Dean demands Sam to tell him why he trusts Ruby. In flashback we find out that while Dean was dead Lilith had released Ruby from Hell, on the condition that she would kill Sam. She instead kills the demon with her and tells Sam she is there to help him. A grief-stricken Sam rejects her help, and demands that she vacate the body she is possessing.
Ruby then possesses the body of a woman in a coma who is brain dead, and whose soul has left her body, and returns to Sam. She offers to help Sam use his powers so he can take revenge on Lilith and he accepts. He is unsuccessful at first in exorcising demons, and becomes even more despairing. Ruby tells him things will get better with time, and seduces him. After that, Sam finds omens that lead him to Lilith and he pursues her despite Ruby's warning not to. Sam walks into a trap, and is attacked by two demons until he is rescued by Ruby. She kills one with her knife and Sam successfully exorcises the other.
She later possesses the body of a maid at the hotel where Sam and Dean are so she can warn them that demons are closing in on them.
Sam and Dean meet up with Ruby and Anna, where they are confronted by Castiel and Uriel.
4.10 Heaven and Hell
After Anna repels Uriel and Castiel, Sam, Dean, Ruby and Anna take refuge at Bobby's place. Pamela Barnes arrives and helps Anna remember that she was an angel who chose to be human. They travel to Kentucky searching for Anna's Grace, only to find it gone. Anna then receives a message that unless Dean hands her over to the angels, they will send Dean back to Hell.
Ruby goes to a crossroads and reveals herself to Alastair. She offers to give up Anna, if Alastair will let her and the Winchesters go. He captures and tortures her with her knife. She won't reveal Anna's location verbally, but she will take him there.
Ruby takes Alastair to where Anna and the boys are and the demons and angels attack each other. Anna get's her grace back from Uriel. During the process, Alastair disappears. Uriel and Castiel leave, and we find out that Ruby was part of Sam's plan to bring the demons and angels together to get them to fight each other.
4.12 Criss Angel Is a Douchebag
Ruby accuses Sam of wasting time - thirty-four of the seals have been broken. Sam says that he doesn't know where the seals are or how to stop them from being broken. Ruby counters that he needs to go after the source of the problem - Lilith. Sam refuses and Ruby leaves.
Later Sam has a conversation with Dean in which Dean says he doesn't see that he and Sam could have a happy future. This leads Sam to rejoining Ruby and the hunt for Lilith.
4.16 On the Head of a Pin
Sam and Dean are heading to meet Ruby, who has some leads on Lilith, when Castiel and Uriel kidnap Dean so he can interrogate Alastair. When Ruby arrives, she uses a spell to help locate where Dean is being held. Sam then tells her that "its been weeks" and he "needs to be strong". Ruby draws a knife across her arm and Sam sucks her blood - the source of his growing powers and abilities.
4.20 The Rapture
Sam calls Ruby, desperate for more Demon Blood but she doesn't answer his calls.
4.21 When the Levee Breaks
After Sam escapes from Bobby's Panic Room and meets up with Ruby. After letting him feed on her, Ruby tells Sam there are only two or three seals left to be broken. She says only "Lucifer's first" can break the final seal - and that is Lilith. This renews Sam's desire to kill Lilith. She says she has a led on a demon close to Lilith who is nearby.
As they prepare to leave, Dean arrives and tries to kill Ruby, but Sam stops him. Ruby leaves as the brothers start to argue.
4.22 Lucifer Rising
Ruby helps Sam capture Lilith's minion who reveals where Lilith will be. After he kills Lilith, Ruby reveals to an appalled Sam that she has been working with Lilith all along to free Lucifer. She tells Sam he didn't need the demon blood, that the choices he has made all year have helped him tap into his own power.
Ruby says Sam was the only one who could brings this about but before she can say why, Dean finally breaks in and rushes forward. Sam holds Ruby as Dean kills her with her own knife.