Clara Oswald, also known as the impossible girl, has arguably been more of a factor in the Doctor's life than any other companion to this point in either Classic or NuWho. While she was mostly familiar with Matt Smith's Eleventh Doctor, she quickly began to accept the Doctor's twelfth and current incarnation, as played by Peter Capaldi. The Eleventh Doctor, at the time of meeting her for the third time in his incarnation's timeline, considered her the only mystery worth solving and it wasn't until the Series 7 finale The Name of the Doctor that the reason he had encountered this girl so many times finally came to pass. The mystery had been solved and Clara had managed to come out the other side as a beloved fixture within the show's mythology, however, if recent speculation are to be believed, her real life alter ego Jenna Coleman will be leaving the TARDIS at the end of this month's Christmas Special, Last Christmas. There are conflicting rumours as well, of course, which suggest she'll actually be staying on for Series 9, so the truth of the matter is that nobody really knows what the hell's going on. Maybe it's better that way but here's five reasons she should stay for the upcoming series and five reasons why her exit might ultimately benefit our beloved mad man with a box. Let's start with the positives.