9. The Doctor Owes Her
In the aforementioned Series 7 finale, The Name of the Doctor, Clara jumped into the Doctor's time stream, despite the fact she wasn't fully aware of the risks, to save him from the Great Intelligence by becoming "echoes" of herself throughout various points of the Time Lord's life. Not only did she end up surviving but she was able to thwart the Great Intelligence at every turn and save the Doctor on numerous occasions - she even pointed out which TARDIS he should captain before he originally left Gallifrey. No other companion can claim to have helped the Doctor as much as Clara ultimately has and it would be a shame for the girl who has literally saved his lives to go about her merry way or to face some unfortunate fate in the Christmas Special.