Doctor Who has change and evolution ingrained in its DNA, a trait that is both one of its biggest selling points, as well as its most forefront point of contention among fans.
Whenever the show gets a major refresh in the form of a brand-new Doctor, it's exciting to see how the latest actor to play the Time Lord will fare in the role, but at the same time, it's sad to see a great Doctor pass the torch and leave the TARDIS behind.
Despite the heartbreak that a Doctor's regeneration can bring, one of the reasons the show has been able to survive over 50 years - when so many others have come and gone in a fraction of that time - is because it's able to grow, adapt and change.
Doctor Who simply wouldn't be Doctor Who without a different actor portraying the main character every couple of years, but that doesn't mean we have to like each incarnation. Every Doctor Who fan has their favourites and least-favourites, and of the 13 main faces we've seen so far, some definitely stand out above the rest.
13. The Thirteenth Doctor (Jodie Whittaker)
At this stage, it's hard to judge where Jodie Whittaker will fall in the Doctor Who hall of fame, since we don't have the complete picture of her tenure. Some Doctors have poor first seasons but redeem themselves further into their era, so by the time she regenerates, Thirteen could end up with a much higher spot in rankings like these.
But based on the single season we have so far (with at least one more to come) Whittaker's Doctor is the weakest of the thirteen main incarnations. Neither as intimidating as Hartnell, as fiery as Tennant or as likeable as Smith, she's far too nice to ever feel truly imposing. She gets the job done in terms of saving the day, but she never seems like a wise, ancient Time Lord while doing it.
By trying to make the eleventh series of the revived show more accessible, showrunner Chris Chibnall stripped the Doctor of her dark edge and super-duper alien weirdness, elements the character really needs. Because of this, Thirteen is a bit of a stock, standard, simplified Doctor: just your run-of-the-mill sci-fi heroine. We didn't even get one of the Doctor's signature epic speeches from her, which was disappointing.
On the plus side, there is room to improve, and with one season safely in the can, hopefully Chibnall and Whittaker decide to take a few more risks with the character going forward.