Doctor Who

Alex Kingston joined Doctor Who as the mysterious River Song in the two-part episode Silence In The Library/Forest Of The Dead during the fourth series of the popular BBC drama.
 'Hello Sweetie!'
When the character was first introduced, much about her origins remained a mystery. Following the character's initial appearance, Davies had described her as "one of the most important characters" in the narrative, and "vital" to the Doctor's life. In series six (2011), Moffat's episodes unveil more about the character. Born Melody Pond, River is the daughter of the Eleventh Doctor's companions Amy Pond (Karen Gillan) and Rory Williams (Arthur Darvill), alongside whom Kingston had appeared several times in series five (2010). Having been conceived in the TARDIS as it travelled through the space-time vortex, Melody is born with genetic traits and abilities similar to the Doctor's own race, the Time Lords.
'Then you may kiss the bride!'
'Ill make it a good one!'
'You better!'
River Song first appears in the Doctor Who 2008 series two-parter "Silence in the Library"/"Forest of the Dead" (written by Steven Moffat) in the Russell T Davies era of Doctor Who. Here, she encounters the Tenth Doctor (David Tennant) in the 51st century, and claims to be someone he will come to trust completely.
'This is River Song back in her cell. Oh and i'll take breakfast at the usual time!'
River, who wears a space suit, carries a TARDIS-colour/pattern diary of her adventures, and is a professor of archaeology, is able to convince the Doctor of his future trust in her by whispering his real name into his ear. The adventure in the Library is River's last real-life encounter with the Doctor in her chronology, but is their first encounter in his. In the second of the two episodes she sacrifices herself to save the people who were trapped in the Library's database, before the Doctor could do the same. In turn he is able to upload her consciousness into a computer, in which she is able to live on in a virtual world created by the Library computer. He achieves this via the use of a sonic screwdriver given to her by his own future self. According to Moffat in the accompanying Doctor Who Confidential episode, River's blaster gun is the one previously owned by Captain Jack Harkness (John Barrowman) in the 2005 series.
 'What in the name of sanity have you got on your head?'
'Its a fez.I wear a fez now. Fezzes are cool!''
After Moffat took over from Davies as executive producer of the show, River Song appeared in the 2010 series. At an earlier point in her timeline, in the two-parter "The Time of Angels"/"Flesh and Stone", River encounters the Eleventh Doctor (Matt Smith), with and to whom she is more familiar. At this stage, River is a doctor and not yet a professor. She leaves coordinates for the Doctor to eventually find so that he may rescue her in the 51st century, and with him she investigates the crash of the spaceship Byzantium.
'Doctor how come she can fly the TARDIS?'
'Oh I had lessons from the best!'
'It's a shame you were busy that day!'
She shows herself to be seemingly more adept at flying the TARDIS than he is and reveals to the Doctor that she is imprisoned for killing, in her words, "the best man I've ever known." An even earlier version of River appears to assist the Doctor in series finale "The Pandorica Opens"/"The Big Bang". After she is contacted in prison by Winston Churchill (Ian McNeice), she leads the Doctor to 102 A.D. Whilst River is travelling in the TARDIS on her own, it explodes with her inside. The Doctor, using River's vortex manipulator, is able to save her and teleport her out. She then assists him in closing the cracks in the universe.
''I was born to kill The Doctor!'
'Demons Run. Remember? This is what they were building. My bespoke pyschopath!' 
'I'm all yours Sweetie!'
After the Doctor erases himself from history in order to completely close the cracks in the universe, River helps Amy Pond to remember the Doctor and bring him back, by giving Amy her now-blank diary. At the close of the series finale, River teases the Doctor when he asks her whether she is married. She ambiguously suggests that yes she is married, and answers yes to a question she pretends to construe as a marriage proposal. She then states to the Doctor that he will soon learn the truth about her, after which 'everything changes'.
 'I'm not going to be there to catch you, every time you feel like jumping out of a spaceship!'
'And you are so wrong!'
In 2011 series opener "The Impossible Astronaut"/"Day of the Moon", River, along with companions Rory (Arthur Darvill) and Amy (Karen Gillan), is contacted by a future version of the Doctor to convene in the United States. This Doctor is killed by an assailant in a space suit, and the trio give him a Viking funeral.
'It's me. I'm Melody. I'm your daughter!'
In 1969, the present Doctor and company subsequently encounter a little girl (Sydney Wade) who wears the space suit, which River tells the Doctor is a life support unit; the suit has been designed by the hypnotic alien Silence. Homeless, the girl is later shown regenerating in New York City, 1970. In "A Good Man Goes to War," it is revealed that River is Amy and Rory's daughter Melody, who was conceived in the TARDIS and consequently carries Time Lord DNA.
'I'm River Song. Check your records again!'
Baby Melody is kidnapped by Madame Kovarian (Frances Barber) to become a weapon against the Doctor. "Let's Kill Hitler" establishes that Melody was trained by the Silence to kill the Doctor. After regenerating in New York, Melody became Rory and Amy's childhood friend Mels (Maya Glace-Green) and grew up alongside them. When adult Mels (Nina Toussaint-White) is shot, she regenerates into her next incarnation (Kingston) and proceeds to assassinate the Doctor.
'Tip for you all: Never shoot a girl when she's regenerating!'
Persuaded she will one day become River Song, in whom the Doctor places great trust, Melody chooses to resurrect the Doctor with her regenerative energy, losing the ability. The Doctor learns, however, that it is she who kills him in his future. The Doctor gives her a blank TARDIS-shaped diary, and Melody—now River—enrolls to study archaeology. At the end of "Closing Time", on the day she receives her doctorate, the Silence and Kovarian recapture River and place her in the space suit to kill the Doctor as history records. In series finale "The Wedding of River Song", River resists killing the Doctor, creating an alternate reality. The Doctor marries River and convinces her to return to the established course of events by letting her know how he plans to fake his death; River goes to prison for his murder to corroborate the deception.
'Ooh I could just kiss you all day!'
'And I you, Miss Kingston!' 
Discussing her role alongside Tennant and Catherine Tate (Donna Noble) in her 2008 introductory episode, Kingston said, "We just clicked. I've done guest roles on other shows, but rarely have I felt such a warm bond." About working with Kingston, Catherine Tate said, "I'm a huge ER fan. When you hold people in awe, it's almost a disappointment when they come in and they're utterly normal. But Alex isn't disappointing at all. She's such a lovely person." David Tennant was quoted as saying, "Alex is terrific. When she's telling you stories about hanging out with George Clooney, you know she's pretty cool."