River Song was created by Doctor Who writer Steven Moffat for the show's fourth series in 2008, under the tenure of executive producer Russell T Davies.
She shows herself to be more adept at flying the TARDIS than he is and reveals to the Doctor that she is imprisoned in the "Stormcage Containment Facility" for killing "the best man I've ever known." An earlier version of River appears to assist the Doctor in the series finale "The Pandorica Opens"/"The Big Bang".
Other actresses have subsequently portrayed younger versions of the character.
When the character was first introduced, much about her origins remained a mystery.
River, who is a professor of archaeology and carries a TARDIS-colour/pattern diary of her adventures, is able to convince the Doctor of his future trust in her by whispering his real name into his ear; which he explains he would only divulge under rare circumstances.
In the second of the two episodes she sacrifices herself to save the people who were trapped in the Library's database, knocking out the Doctor before he can do the same.