Top 5 Doctor Who companions
Back when I was a kid, and Doctor Who still knew it was a kids' show, and the only adults who liked it knew way too much about the backstory to the Dalek empire, the best assistant was played by Sophie Aldred. Her slightly improbable name was Ace, she wore a leather jacket, and she was an absolute badass. Ace had been expelled from school for blowing up the chemistry lab and her main character trait was throwing cans (cans!) of nitroglycerin (presumably - it's called nitro-9) at aliens as they came over the ridge of some quarry or other. Makes me all nostalgic, actually. Forget all this Rose and Catherine Tate nonsense - bring back Sophie Aldred!
2. Much-loved Blue Peter presenter Peter Purves was in Doctor Who! He gets a place here for being one of only a handful of male companions the Doc has had in recent centuries. He's a doer rather than a thinker, and, like Lister in Red Dwarf, the suggestion is that he's an 'enlightened 23rd century guy'.
Everyone's fave character, and the most faithful companion of all was surely K-9. There have been four K-9s in total, although just like that hamster you had that lived for 25 years, it's unlikely anyone noticed the changes. Wikipedia says K-9 "suffered from numerous technical problems during its time in the series, often malfunctioning because the radio controls interfered with the cameras and vice versa. On location, K-9 also proved unable to traverse uneven terrain, and shots had to be conceived with this in mind. Workarounds included using a concealed piece of twine to pull the character along, or laying wooden planks on which it could roll."
4. Rose Tyler
Rose Tyler arrived with Christopher Eccleston, of course, in 2005, and despite several false alarms hasn't quite managed to leave yet. The most exciting thing, initially, was discovering that Billie could act; then we realised we rather crushed on her (as a nation), but now it's starting to feel like we've trapped her in a relationship she's outgrown. Rose used to drop her 'h's and say 'fink' instead of 'think' but in the most recent episodes she seems to have trouble moving her mouth at all when she talks. Rose is much too good for her rubbish on/off boyfriend Micky, and now lives in a parallel universe with a half-human version of the Doctor.
5. Lalla Ward's character - Romana II. Lalla Ward played a Tom Baker assistant, and gets mentioned here because of her excellent personal life. She's married to Richard Dawkins, and they were introduced by their mutual friend, Douglas Adams! Imagine that! She was also briefly married to Tom Baker. Already more interesting than Bonnie Langford, eh?