Steven Moffat deliberately chooses "odd" looking people to step into the role of the Time Lord.
The 'Doctor Who' executive producer believes the beauty of the titular time-travelling Gallifreyan lies in his charm and intelligence, so unconventionally attractive actors like Matt Smith and Peter Capaldi are perfectly suited to the role.
He explained to Radio Times magazine: "There's something about Peter's demeanour, his eyes, his attitude - he's tremendously bright and that comes out on screen. When you choose a Doctor, you want somebody who is utterly compelling, attractive in a very odd way.
"None of the Doctors are conventionally attractive, but they're all arresting. Handsome men don't quite suit. Matt Smith's a young, good looking bloke from one angle but actually the strangest looking man from another.
"You need that oddity; you need somebody who is carved out of solid star, really. It really is built around the abilities, the charm and the magnetism of a succession of different actors."
Steven also seeks stars with an ageless quality about them and likes the combination of boyish behaviour and an air of wisdom that new Doctor Peter possesses.
He said: "I always thought Matt, while a very young man, had something of the demeanour of a much older man, whereas Peter is a man in his 50s but terribly boyish and young at times. I like the Doctors to have mixed messages about what age they are - you can't really pin them down."
Tagged in Matt Smith Steven Moffat Peter Capaldi