From an actor's perspective, one of the strange things about joining Doctor Who must be the short-term nature of the job. If you're entering the Whoniverse as a companion or even as a Doctor, you know you're only going to be there for two or three years, at which point, you'll essentially be replaced - and the show will continue on.
But even though most actors probably have this rough end date in mind from the moment they set foot in the TARDIS, that doesn't mean they won't end up feeling regretful when those last moments finally arrive.
Whether their tenure ended on a sour note or they felt like they had more to give, some Doctor Who actors feel huge regret over their decisions - whether voluntary or forced - to leave the show. And hell, you can't blame them - a lot of fans would crawl across ten miles of broken glass just to smell David Tennant's old PE shoes.
Now yes, every Doctor Who actor probably regrets leaving the show in some small way, but here are a few stars who actually spoke about these feelings publicly.
8. Elisabeth Sladen
During her initial run in the classic series, Elisabeth Sladen worked with two Doctors over a three-year period, appearing in four separate seasons to boot. She became a fan-favourite, an important part of the show, and an icon in her own right.
Because of how well her tenure was received, Sladen felt quite fulfilled when the time came for her to move on, and she was pleased with what she'd managed to achieve.
However... she did also feel a touch of regret.
In an interview from the 1980's, Sladen talks about how her Doctor Who exit was entirely her decision, and how she was pleased that none of the BBC higher-ups gave her "a quiet push". At the same time, she also says that she "felt regret" about leaving, presumably because a part of her wanted to stick with the show for even longer.
With hindsight, we now know that Sladen's relationship with Doctor Who was far from over (she even ended up getting her own spinoff), but back then, she probably thought she was done for good, so it's no surprise that she felt that small twinge of regret.