Very much a niche kind of death, and precisely the sort of thing which only really happened back in the day when the First Doctor was knocking about, threatening to bash weak members of the groups skulls in as they were slowing everyone down, as he does in the very first serial. The very first death of a companion came in the 1966 serial The Daleks Master Plan, when Sara Kingdom and Katarina get themselves killed. Katarina gets sucked into the vacuum of space via an airlock in order to save others' lives from a mad fugitive called Kirksen, but Sara's death was quite different. Concerned about the Doctor's meddling with a Time Destructor, a device which can accelerate the passage of time, she gets caught in its beam and goes the same way as that chap from Indiana Jones and the Last Crusade. She ages to death. Well, we all age to death to some extent, but she does it super-efficiently and turns to dust. As much as the Doctor's not a space-based babysitter, it's still kind of his fault that he doesn't make sure Sara's gone back to the TARDIS with everyone else before accidentally killing her. There's certainly an outside chance that the Doctor's carelessness or miscalculations might end up being the end of Clara. After all, she's been banging on about wanting to have more adventures a lot lately - the Doctor's willingness to indulge her might ultimately be her undoing.
