Doctor Who ran on the BBC from 1963 until it was cancelled in 1989.
During that time the Doctor was played on TV by seven different actors - and reappeared in a one-off TV movie in 1996.
- A grandfather figure, often quite grumpy but with a kind heart. He was the first Doctor to battle the Daleks and the evil Cybermen.
- A much quirkier Doctor than before. He was scruffy, with baggy trousers and loved playing a recorder. He fought many classic monsters such as the Yeti and the Ice Warriors.
- A Doctor with a love of gadgets, frilly shirts and fast cars - including the flying saucer-like Whomobile. Many of the third Doctor's stories were set on Earth, where he battled Autons, Axons, Sea Devils and giant maggots! He also faced a new enemy in the form of The Master - a rogue Time Lord - who was to reappear many times over the years.
- The Doctor that most adults remember for his long stripy scarf, curly hair and love of jelly babies. He was an energetic Doctor, always ready to wind up a monster with a witty retort. He also had a pet robot dog called K9.
- Youthful and fond of cricket. He had one memorable adventure when he met his four other selves in a story called The Five Doctors. Also battled Daleks, Cybermen and Sea Devils. He regenerated after he sacrificed one of his lives to save his assistant, Peri.
- Had a terrible dress sense! The Doctor was moody and aloof, and often argued with his companions. It was during the Sixth Doctor's era that audience ratings were low and in 1985 the BBC announced that the show would be taking a break - much to the anger of loyal Doctor Who fans.
- The Seventh Doctor began as a comic figure but soon developed into a much darker character. His umbrella had handle shaped like a question mark. He was also good at juggling and playing the spoons. He had a feisty companion named Ace who even destroyed one Dalek with a baseball bat!
- The Doctor reappeared in an American-backed TV movie battling The Master in an adventure set on New Year's Eve, 1999. The film did well in the UK, but was not so successful in the US and wasn't made into a series.
- After an absence of 16 years, Doctor Who returned to BBC1, sporting a skinhead, leather jacket and northern accent. And why not? Doctor Who was back with cool special effects, modern storylines and a strong-willed female assistant called Rose, played by ex-pop star Billie Piper.
- After one successful season, Christopher Eccleston decided to leave and Doctor Who regenerated into actor David Tennant. A different kind of Doctor, he wears a brown suit, a raincoat and, er, white trainers. He looks quirky.
- The 11th Doctor will be played by 26-year-old actor Matt Smith. He takes the keys to the Tardis in 2010, and in the first pictures of him as the Doctor he looks very cool and moody.