1. Sarah Jane Smith
For my imaginary money, though, the best departure that Doctor Who has ever seen is that of Sarah Jane Smith. Sarah Jane was one of the most popular companions, and is still the favourite of many. She was the brave journalist, seemingly the perfect companion for two doctors. She was smart, and strong and stayed in the TARDIS for so long that she felt like part of the show. It's easy to understand why she's just so beloved. And, so, it's also easy to understand why her departure is just so good. It came at the end of a slightly mediocre story, yes, but it's very well-judged and entirely heartbreaking. Watching the two characters say goodbye to each other after so long you feel genuinely emotional, and when Sarah Jane steps out of the TARDIS for the final time it's very hard to hold back tears. Sarah Jane was a firm favourite of the audience, yes, but she was also obviously a firm favourite of the show. This is shown in the relative dignity of her departure, and the focus that they gave her. To toss Sarah away halfway through a story would've been inappropriate, instead they give her a whole story and a goodbye scene that feels gloriously long. She is even given the final shot of the episode, a freeze-frame that shows just how important she was and will always be to the show. And how important she was to the actors, too. A scene was apparently scripted, but was largely thrown aside in favour of something private that Lis Sladen and Tom Baker had worked out together. The result is something quietly beautiful, an understated scene that conveys just how deeply the two characters felt about each other. They were best friends, apparently in real life as well as in the show, and that is carried across perfectly in their final scene. We often hear of how much companions mean to the Doctor, but it is very rare to see it. Sarah Jane Smith was one of the most popular characters that Doctor Who has ever produced, and her ending had to be wonderful as a result. As it was, it turned out absolutely perfect. A lengthy, thoughtful thing that showed just how much she meant to the actors, the producers and the show in general. She was given a proper, dignified send-off that proved the perfect bookend to her first period of time with the Doctor. And, really, she showed that the best way to convey meaning is through an absolutely perfect ending.