The first companion to be killed, and in just her second story and after having appeared in just 5 episodes. A run so short that some don’t consider her to be a companion, although she traditionally has been considered as such and is included on this list. Her departure is not higher up the list because we don’t get a chance to truly know her character or invest our emotions in watching her as much as we would a long-running companion - but the shock value at the time must have been tremendous. Introduced in the final episode of the preceding story The Myth Makers (in very similar fashion to her fellow TARDIS traveler Steven Taylor, who was introduced in the final episode of The Chase), the audience sees her replace Vicki in the TARDIS and naturally assumes that she will be the new companion for quite some time. Four episodes into The Daleks’ Master Plan the audience is shockingly proved wrong. Doctor Who‘s unpredictability went up a notch, and while she was there a short time, her tragic but heroic exit means that her departure was a memorable one (or would be if most fans had seen the story - check out the audio though, it is fantastic).