Clara Oswald is one of the Doctor's most extraordinary companions. In order to help the Doctor she allowed the time winds to tear her into countless different iterations of herself, or as River phrased it, ‘A million versions of you, living and dying all over time and space, like echoes.' These different Claras helped the Time Lord on many occasions, with one of them even persuading the First Doctor to steal the TARDIS that became ‘his' time machine.
(Source: BBC)
