7. Katarina
Katarina has been a bit screwed over by history. She appears in one full surviving episode, but apart from that nothing but the record of her departure has survived. This seems a great pity a Trojan priestess off to see the stars, while apparently believing that she was dead and in the company of Zeus in the form of the First Doctor, was an absolutely fascinating idea and may have really worked. Her character concept was considered far too complicated, however, and she was killed in the most dramatic way possible. And this is not hyperbole. Even with limited build-up Katarina's departure is absolutely chilling. Dragged into an airlock by a madman, she sacrifices herself to save the Doctor and her friends. It's a scene of great emotional resonance, even if you have no attachment to the character. Hearing her screams and watching her struggle is enough to strike to the very bone, and when she reaches for the release switch as Steven (Peter Purves) desperately yells for her to stop... Well, many goosebumps are raised. It's also admirable in how daring it was. The death of significant characters is rare in Doctor Who, even in the modern revival. Companions either depart willingly or are torn away, they very rarely die. Katarina, however, does die and becomes the first companion to do so. She opens up new ground, and perhaps enables equally dark departures in the future the four companions who had departed before Katarina went largely willingly, the change after her wasn't entirely immediate (not counting Sara Kingdom) but it can definitely be said to have eventually led to the heartbreaks of the future. Sixties Doctor Who can sometimes be ridiculous, yes, and I doubt that even the most hardcore fan would deny that there were a few major fumbles. But it laid the path for the programme that we know and love today, and was often genuinely great TV on its own merits. Katarina's death is one of those moments that shows just why Doctor Who has lasted so long, and shows just how good the programme can be. It is chilling, it is striking and it is such an incredibly brave choice that it deserves admiration. Katarina barely had the chance to be a companion, but in her departure she became truly wonderful nonetheless.