The Tenth Doctor is a study in contrasts. He's charismatic and slightly manic, possessing a disarming sense of humour borne of his seemingly boundless energy. He's also staunchly heroic, leaping into the fray like a slightly demented Errol Flynn. But there is an undeniable shadow cast over the jollity of the Tenth Doctor. He is not a man to be crossed heedlessly; when driven to anger, he will act without hesitation to strike down those who oppose him. His ruthlessness, bordering on arrogance, is almost eerie to behold. Beneath his youthful veneer, the Tenth Doctor is a very old man who has seen many terrible things; and in some matters, his patience has worn out.

David Tennant has played the Doctor since The Parting Of The Ways in June 2005.

When the Doctor first met Donna Noble, she was obnoxious, self-centred and occasionally quite thick. Almost immediately, however, the Doctor's influence helped transform Donna, awakening her to the wider world outside her own narrow experiences, and the enormous possibilities that life offers. Donna, too, was a crucial presence in the Doctor's life, at first providing him with a touchstone to the everyday, and later proving herself strong-willed enough to challenge him, and show him that even a Time Lord is not always right. At the heart of Donna Noble is a confident, determined and resourceful woman... and even the tragic end of Donna's time with in the TARDIS can't diminish that.

Catherine Tate played Donna from Doomsday in July 2006 to The Runaway Bride in December 2006, and from Partners In Crime in April 2008 to Journey's End in July 2008.

A medical student well on her way to becoming a doctor herself, Martha Jones was, in many respects, the soul of maturity. A conciliator and a healer by nature, Martha was resistant to being pushed around or patronised, and was unafraid to be blunt and to-the-point when she thought the situation demanded it. She knew what she wanted, and she was determined enough to get it -- or to recognise, before it was too late, that it was unobtainable. Nonetheless, Martha was still young, and there was a part of her that chafed under the weight of her assumed responsibilities: a part of her that yearned for exploration, and adventure.

Freema Agyeman played Martha from Smith And Jones in March 2007 to Last Of The Time Lords in June 2007, from The Sontaran Stratagem in April 2008 to The Doctor's Daughter in May 2008, and in The Stolen Earth / Journey's End in June/July 2008.

Astrid Peth always dreamt of the stars, and the alien skies beyond them. Even as a child, she was mesmerised by the sight of spaceships climbing to the heavens, and once she was old enough, she took jobs to be closer to them -- even if that meant employment as a mere waitress. Finally hired as a stewardess aboard the ersatz starship Titanic en route to Christmastime Earth, Astrid quickly formed an allegiance with the Doctor when disaster struck. There she proved herself kind, resourceful and almost heedlessly courageous, determined to do the right thing without even contemplating the consequences.

Kylie Minogue played Astrid in Voyage Of The Damned in December 2007.

The announcement of the new Doctor Who series' fourth season came at the launch party for its third slate of episodes, on March 21st, 2007. During the filming and broadcast of the season, it was revealed that all three key production team members -- Russell T Davies, Julie Gardner and Phil Collinson -- were planning to leave Doctor Who. The fourth season thus became an embodiment of the end of an era, reuniting many of the characters who had made their mark since Doctor Who's return in 2005. Davies also continued to gradually resurrect classic characters from the original series, introducing both the Sontarans and Davros to a new viewing audience.

But the enduring success of the Doctor Who revival was made emphatically clear when the final episode, Journey's End, rose to the top of Britain's weekly viewing charts -- the first time Doctor Who had ever earned a Number One berth. Coupled with an astronomically high Audience Appreciation index, this meant that Journey's End was not only the most successful Doctor Who episode ever made, but one of the UK's all-time most popular dramas.

For a time, Jackson Lake thought that the Doctor was his companion -- because Jackson believed himself to be the Doctor. His memories clouded by a Cyberman data device and the tragedy of his wife's murder, Jackson took to the streets of 1851 London, attempting to fulfill the Time Lord's role. And as the real Doctor himself would later observe, the deeds were not influenced by Jackson's delusion, but rather were proof of the man's own courage and determination. The Cyberman device may have bequeathed him factual information about the Doctor's past, but it was Jackson's own character that shone through as he strove to save London from the Cybermen.

David Morrissey played Jackson in The Next Doctor in December 2008.

Vivacious, daring, and seemingly fearless, Lady Christina de Souza in many ways reminded the Doctor of himself. Despite a noble heritage, Christina was a born thrillseeker: rather than stealing a time machine to escape a culture of stultifying somnolescence, the de Souza family's recent financial ruin was all the excuse Christina needed to embark upon a career as a death-defying cat burglar. Like the Doctor, Christina was charming, resourceful and a born leader, equally adept at thrusting herself into danger as recognising and relying upon the expertise of others. Christina may have been denied a place in the TARDIS, but there is little doubt that many more adventures awaited her after her adventure with the Doctor.

Michelle Ryan played Christina in Planet Of The Dead in April 2009.

On September 3rd, 2007, it was announced that Doctor Who had been renewed for a fifth season, but that this would not be broadcast until 2010. To bridge the gap, the traditional Christmas special -- The Next Doctor -- aired in December 2008, and will be followed by four specials broadcast during 2009 and 2010; both David Tennant and Russell T Davies will be remaining with Doctor Who for these specials. Of the four 2009/2010 specials, the first will air at Easter (in April), and one at Christmas. The last special will apparently air on or around New Year's Day 2010. The Next Doctor was filmed immediately upon the completion of the 2008 season, while production began on the remaining specials on January 19th, 2009, with filming taking place in High Definition for the first time.

The Next Doctor was written by Russell T Davies, and features the Cybermen in Victorian England. He will also write Episode 61 / Episode 62, which will form a two-part story. Planet Of The Dead saw Davies joined by co-author Gareth Roberts (who wrote The Shakespeare Code and The Unicorn And The Wasp, and who has already co-written the original episode of The Sarah Jane Adventures, Invasion Of The Bane, with Davies), while The Waters Of Mars will see him paired with Phil Ford (who wrote Eye Of The Gorgon and The Lost Boy for The Sarah Jane Adventures, and Something Borrowed for Torchwood).

The Next Doctor was directed by Andy Goddard, who has helmed six episodes of Torchwood, including Adam and Dead Man Walking. Planet Of The Dead was directed by James Strong, whose credits to date include The Impossible Planet / The Satan Pit and Voyage Of The Damned. The Waters Of Mars will be directed by Graeme Harper, who has directed stories spanning The Caves Of Androzani to The Stolen Earth / Journey's End. Episode 61 / Episode 62 will be directed by Euros Lyn, whise extensive Doctor Who resume includes The End Of The World, The Girl In The Fireplace, The Runaway Bride, and Silence In The Library / Forest Of The Dead.

Each special will see the Doctor joined by a temporary “companion”. In The Next Doctor, this was Jackson Lake, played by David Morrissey (Blackpool, The Knock, State Of Play, and features films such as The Other Boleyn Girl and Captain Corelli's Mandolin); in Planet Of The Dead, this was Lady Christina de Souza, played by Michelle Ryan (EastEnders, Bionic Woman, Jekyll, Merlin). They will be followed in The Waters Of Mars by Lindsay Duncan (Rome, Spooks, G.B.H. and movies including An Ideal Husband and Under The Tuscan Sun) as Adelaide; and in Episode 61 / Episode 62 by Bernard Cribbins, returning to the role of Donna Noble's grandfather, Wilfred Mott, which he played from Voyage Of The Damned to Journey's End. In addition, Catherine Tate will also appear as Donna Noble in Episode 61 / Episode 62.

On December 11th, 2007, it was revealed that these specials would be the final Doctor Who episodes made under the aegis of executive producer Julie Gardner. Gardner would be relinquishing these duties at the same time as she stepped down as Head of Drama for BBC Wales, in January 2009. Her successor as both Head of Drama and Doctor Who executive producer will be Piers Wenger.

On February 1st, 2008, a further departure from the production team was revealed with the announcement by the BBC that producer Phil Collinson has been appointed Head of Drama for BBC Manchester. Collinson left Doctor Who upon the completion of the 2008 season. Susie Liggat will produce The Next Doctor. Nikki Smith, the new producer of The Sarah Jane Adventures, will assume the same role on The Waters Of Mars; on Doctor Who, she previously served as script editor for The Sontaran Stratagem / The Poison Sky. Planet Of The Dead and Episode 61 / Episode 62 will be produced by Tracie Simpson, a production manager on the series since Rose.

On May 20th, the most significant behind-the-scenes change was confirmed with the revelation that Steven Moffat would be replacing Russell T Davies as both executive producer and head writer beginning with Doctor Who's 2010 season. In addition to writing The Empty Child / The Doctor Dances, The Girl In The Fireplace, Blink and Silence In The Library / Forest Of The Dead, Moffat has also served as executive producer for Coupling and Jekyll, and has written for programmes such as Press Gang, Chalk, Joking Apart and Murder Most Horrid. Moffat has also written the screenplay for the 2009 Tintin feature film, produced by Peter Jackson and directed by Steven Spielberg.

On October 29th, the BBC confirmed that David Tennant has decided to leave Doctor Who after the final special. Tennant has admitted that he worried that he might never quit the show unless he forced himself to go, and felt that departing alongside Russell T Davies and Julie Gardner would be the best way to do it, clearing the slate for Steven Moffat in 2010. On January 3rd, 2009, Matt Smith was revealed to be Tennant's successor; he will be accompanied by a new character played by Karen Gillan.

Doctor Who: A Brief History Of Time (Travel) would like to take this opportunity to extend its thanks to David, Russell, Julie and Phil for their incredible efforts during the past several years, and for reaffirming Doctor Who's place amongst the all-time great television programmes.

On April 15th, the BBC announced that Doctor Who would have two full-time producers beginning with Matt Smith's first season. Tracie Simpson would remain at the reins of the programme, to be joined by Peter Bennett, who produced the third season of Torchwood. In the past, Bennett has worked chiefly as an assistant director, with credits encompassing everything from the feature films Moonraker, Young Sherlock Holmes, The Princess Bride and The Mummy to the television programmes Minder, Inspector Morse, Poirot and Sea Of Souls. No newcomer to Doctor Who, he was a first assistant director on episodes beginning with Bad Wolf; he also served in that capacity on the Torchwood episodes Everything Changes and Day One.

In addition, the BBC also announced on April 15th that Doctor Who will have a third executive producer for the first time since the 2005 season. Joining Steven Moffat and Piers Wenger will be Beth Willis. Willis got her start as a script editor, working on programmes such as Poirot and The Amazing Mrs Pritchard. More recently, she produced Ashes To Ashes before being tasked to join Wenger on a variety of dramas from BBC Wales.