Clara Oswald is a companion of the Eleventh and Twelfth Doctors. The Doctor considers her “impossible” due to her being present in different ‘incarnations’ throughout different points of his timeline, which is later revealed to be the result of Clara being shattered into millions of ‘echoes’ dispersed along the Doctor’s timeline. After the events of Trenzalore, Clara becomes an English teacher at Coal Hill School but continues travelling with the Doctor, even meeting other of his incarnations, such as the Tenth and War Doctors. Growing increasingly more reckless with time, Clara dies when she takes a Chronolock from her friend Rigsy, in order to save him. The Doctor takes Clara from the fixed point of her death in her timeline with the help of an extraction chamber in Gallifrey, with her becoming stuck “between one heartbeat and the next”. Trying to bring Clara fully back, the Doctor steals a TARDIS and flees from Gallifrey to the end of the Universe, but his plan doesn't work. The Doctor then decides to erase Clara’s memory of ever travelling with him, but has all his memories of Clara erased instead. Clara leaves the Doctor, taking the stolen TARDIS with her, intending to travel back to Gallifrey “the long way around”.