The Doctor

The Doctor is the title character in the Doctor Who series. He is a Time Lord from the planet Gallifrey, who wanders through time and space in his ship, the TARDIS. For the most part, and usually because the vessel's navigation system is old and unreliable, he explores the universe at random and uses his extensive knowledge of science and advanced technology to heroically avert the crises that he encounters. The Doctor has, at various times, been accompanied by companions who have chosen to travel with him for a variety of reasons.

The Doctor is considered a renegade by his fellow Time Lords, for his penchant of getting "involved" with the affairs of other worlds, in direct violation of official Time Lord policy. However, most of the time his actions are tolerated, especially when he has saved not just Gallifrey, but the universe, several times over. His standing in Time Lord society has waxed and waned over the years, from being a hunted man to even being appointed Lord President of the High Council (an office he did not assume for very long and eventually was removed from in his absence). In the end, though, he has always seemed quite content to remain a renegade and an exile.

The character was first portrayed by William Hartnell in 1963. When Hartnell left the series in 1966 , the role was taken over by Patrick Troughton. To date, eight actors have played the Doctor on television, with perhaps the most enduring incarnation being the fourth, played by Tom Baker. Christopher Eccleston will play the Ninth Doctor in a new series to debut in March of 2005.

When the series begins, nothing is known of the Doctor at all, not even his name. In the very first serial, An Unearthly Child, two teachers from the Coal Hill School in London, Barbara Wright and Ian Chesterton, become intrigued by one of their students, Susan Foreman, who exhibits high intelligence and unusually advanced knowledge. Trailing her to a junkyard at 76 Totter's Lane, they encounter a strange old man and hear Susan's voice coming from inside what appears to be a police box. Pushing their way inside, the two find that the exterior is actually camouflage for the dimensionally transcendental interior of the TARDIS.

Susan calls the old man "Grandfather", but he simply calls himself the Doctor. When he fears Ian and Barbara may alert the local authorities to what they've seen, he subsequently whisks them all away to another locaton in time and space.

Changing faces

Eight actors (with a ninth to follow) have officially played the Doctor on television. The changing of actors playing the part of the Doctor is explained within the series by the Time Lords' ability to regenerate after suffering mortal injury, illness, or old age. The process repairs and rejuvenates all damage, but as a side-effect it changes the Time Lord's physical appearance and personality semi-randomly. This ability was not introduced until producers had to find a way to replace the elderly William Hartnell with Patrick Troughton and was not explicitly called "regeneration" until Jon Pertwee's transformation to Tom Baker at the conclusion of Planet of the Spiders. On screen, the transformation from Hartnell to Troughton was called a "renewal" and from Troughton to Pertwee a "change of appearance."

Despite the fact that the Doctor is supposed to be the same person throughout his regenerations, each actor to play the Doctor has purposely imbued their incarnation with distinct quirks and characteristics. At his core, however, the Doctor continues to be a heroic figure, fighting the evils of the universe wherever he finds them, even if his values and motives are sometimes alien.

The Nine Doctors

• First Doctor - William Hartnell: (1963 - 1966)

Hartnell played the Doctor as an irascible, grandfatherly type, a brilliant but often short-tempered scientist.

• Second Doctor - Patrick Troughton: (1966 - 1969)

In contrast to Hartnell, Troughton's Doctor was a sort of "cosmic hobo," often frightened of the alien menaces he faced, whose solutions were sometimes of a hit-or-miss nature.

• Third Doctor - Jon Pertwee: (1970 - 1974)

Pertwee's Doctor cut more of a dashing figure than his predecessors, a dandy with a penchant for gadgets and martial arts, particularly "Venusian akido."

• Fourth Doctor - Tom Baker: (1974 - 1981)

Perhaps the most eccentric incarnation, the Fourth Doctor was something of a cross between Willy Wonka and the Mad Hatter, rarely without his signature scarf of incredible length.

• Fifth Doctor - Peter Davison: (1981 - 1984)

The youngest of the Doctors, Davison's incarnation had a fondness for cricket. He was somewhat more nervous and less sure of himself than the two previous Doctors, though no less heroic.

• 'Sixth Doctor - Colin Baker: (1984 - 1986)

Sporting a multi-hued wardrobe that looked as if designed by Christian Lacroix, the Sixth Doctor had a manic personality and an ascerbic wit.

• Seventh Doctor - Sylvester McCoy: (1987 - 1989)

His voice touched by a Scottish burr, the Seventh Doctor combined the vagabound nature of the Second and Fourth Doctors with the scientific brilliance of the First and Third incarnations.

• Eighth Doctor - Paul McGann: (1996) - in the Doctor Who television movie

McGann's Doctor showed a romantic and sensitive side not evident in the previous Doctors, a point of some controversy among fans.

• Ninth Doctor - Christopher Eccleston: - the Ninth Doctor as announced by BBC on 19 March, 2004 for the series revival set to premiere on 26 March, 2005.

It remains to be seen what personality traits the Ninth Doctor will exhibit