River Song is a fictional female Human galactic criminal in the Doctor Who television series who was portrayed on screen by Alex Kingston. River Song is the child of Amy Pond and Rory Williams who made her own way in life after being born. river's catchphrase which uses when she meets people is 'Hello Sweetie'
The Doctor meets River Song at the end of River's life when she is leading an exploration at a library that encompasses the entire planet. At this time in The Doctor's life, he had yet to meet River Song but she knew him well and she had in her possession a sonic screwdriver and knows his name which the Doctor finds a bit baffling. She dies in the second part of the two part story in which we first meet her. She gives her life for the exploratory team and is placed inside the machine that controls the library by the Doctor to live on in virtual reality.
River Song reveals in The Husbands of River Song that she is in love with the Doctor. The Doctor has never been romantic without anyone before. However on this occasion, he takes her to the singing mountains where he has a dinner with her.
Like the Doctor, she has had a few different faces but in the adult phase, she looks the same (played by Alex Kingston). In Lets Kill Hitler where she appears as an adolescent, she appears of mixed-race but then she soon reveals herself.