Harriet Jones: Did you notice when they fart, if you'll pardon the word, it doesn't just smell like a fart, if you'll pardon the word, it's something else. What is it? It's more like, um... Rose Tyler: Bad breath. Harriet Jones: That's it! The Doctor: Calcium decay. Now that Narrows it down!.. Calcium phosphate. Organic calcium. Living calcium. Creatures made out of living calcium. What else - what else? Hyphenated surnames. Yes! That narrows it down to one planet! Raxacoricofallapatorius! Mickey Smith: [sarcastically] Oh yeah, great! We can write 'em a letter.

Wilf: God bless the cactuses! The Doctor: That's cactI. Alien: And that's racist!

You are worthy of love and respect. You are beautiful, gifted, and intelligent. Don't let the storm make you forget it.

In the end I sort of though we created a companion who was so alive and dynamic and so wedded to the doctor that you’d need a whole universe to contain her in. The only way to get rid of her is to send her into a parallel world from which she can never return; otherwise she would stay with the doctor forever.

[David Tennant's] Doctor has such humanity, he seems to understand us and he's very warm, so he's a comforting Doctor to be with, and he enables us to be slightly scarier than we had been.

I love having debates with people when they are debates but some people, you just can't. Some people shouldn't be given the oxygen.

Drama's not safe and it's not pretty and it's not kind. People expect the basic template of television drama where there might be naughty villains, but everyone ends up having a nice cup of tea. You've got to do big moral choices and show the terrible things people do in terrible situations. Drama is failing if it doesn't do that.