5. "Silver Puppet, jumping on a string. String Cut."
A fair while back, I threw out the question on Facebook 'Who was the only one of the Doctor's companions that he actively murdered?' And was only partially surprised to observe that most of fandom has long since forgotten that Kamelion ever existed at all. I should note - I've always been a huge fan of Kamelion because I was a 12 year old boy at the time and a shapeshifting robot was just about the coolest thing ever to me at the time. But outside of that, I also think he has just about the most compelling companion storyline in the history of the show. (And yes, I do consider him to be a companion, if a Katarina-end-of-the-spectrum companion. Clearly that was the intent, and he was obviously lurking around in the ship somewhere. The About Time series has by far the most amusing justification for why he locked himself in his room and refused to come out, I highly recommend checking it out.) The point of Kamelion is - he was the Companion who wasn't good enough. He wanted so badly to have a chance to prove that he could be good, and he
failed. His dying words echo every dark though that any of us have ever had at the moment when we feel most worthless. 'Kamelion... no good. Sorry.' Which makes the Doctor nearly physically attacking him an episode or so earlier heartbreaking and impossible to turn away from. The fact that he's a mechanical being disguised as The Master basically allows us to politely ignore that this is The Doctor's friend. And The Doctor is assaulting him. Imagine any other companion in Kamelion's place and see how brutal it really is. Imagine him treating Tegan that way. Imagine him shooting Sarah Jane.