What defines a companion? For this list, we will be counting those who traveled with The Doctor for a) more than one episode or b) had such an impact in a single episode that they simple can't be left off this list!
Doctor Who, since the revival, has offered a wealth of fresh talent and faces to the audience, giving us all many, many new companions to root for. Some may not have had the impact or longevity we may have wished for, yet all bring something new to the game.
Whether they're locked in a parallel universe or in a prison of blocked memories, many exits on this show can be heart(s)breaking, while still others can walk away alive and well - or at least alive, anyway.
Where does your favourite companion rank here? Read on to find out!
22. Lady Christina De Souza
While Planet of the Dead is perhaps the weakest of the 2009 Doctor Who specials, Michelle Ryan's Lady Christina De Souza brought a cheeky fun to the episode that had been somewhat lacking in previous installments. With the impending knowledge of David Tennant's departure from the role, a heavy weight was on the show.
Thankfully, the episode is a light and fun affair. That is perhaps its weakness in terms of where it lands in the series - the next episode is the horrific Waters of Mars - but, as a stand-alone, it a great adventure.
Lady Christina seems to be always one step ahead and could very well return to the show - never say never!