2008 (production)

January

 * 11 January - Russell T Davies began writing the script for Journey's End.
 * 8 January - According to BBC News, a "long-standing back injury" forced David Tennant to miss several performances of Hamlet at London's Novello Theatre. Ultimately, Tennant underwent back surgery. This affected not only Hamlet, but also the production of Doctor Who.
 * 12 January - Steven Moffat informed Russell T Davies he had begun writing the first episode of series 5

February

 * 7-8 February - The Big Finish audio story Assassin in the Limelight was recorded at the Moat Studios.
 * 15 February - Cast readthrough for The Stolen Earth/Journey's End took place.
 * 25 February - Big Finish's Bernice Summerfield audio story The Adventure of the Diogenes Damsel was recorded at the Moat Studios.

March

 * March - The BBC announced it was investigating technology to return colour to Third Doctor episodes only available in black and white.
 * 4 March - Russell T Davies began writing the script for The Next Doctor, the fourth Christmas special.
 * 10 March - 11 March - AUDIO: The Nightmare Fair was recorded.
 * 17 March - Russell T Davies completed his script for The Next Doctor. (REF: Doctor Who: The Writer's Tale - The Final Chapter)
 * 23 March - Responding to criticism from his correspondent Benjamin Cook, Russell T Davies agreed to change the ending of Journey's End, removing a planned cliffhanger to lead into The Next Doctor.
 * 24 March - Recording for the Iris Wildthyme story The Land of Wonder took place at The Moat Studios.
 * 26 March - Final correspondence between Russell T Davies and Benjamin Cook in terms of material included in the first edition of the book The Writer's Tale took place, but correspondence incorporated into the second edition began immediately.
 * 29 March - Production wrapped on Journey's End, ending production of the thirteen episodes of Series 4 proper, though production continued on the Christmas special, The Next Doctor.
 * 30 March - The first reviews of Partners in Crime appeared in UK newspapers.

April

 * Early April - Review copies of the Fourth Season premiere, Partners in Crime, were circulated to media. Unknown to the media, they received an edited version omitting the surprise cameo appearance by Billie Piper (a ruse acknowledged by Russell T Davies in later interviews and Doctor Who Magazine).
 * 2 April - Cast readthrough for The Next Doctor.
 * 7 April - Filming began on The Next Doctor, the 2008 Christmas special.
 * 9 April - Cast readthrough for The Day of the Clown and Secrets of the Stars took place.
 * 9 April - The BBC announced that Doctor Who and composer Murray Gold would be spotlighted in Doctor Who at the Proms, a special concert during the upcoming Proms classical music performance series. At a press event, violinist, there to promote his own Proms appearance, performed his own arrangement of the Doctor Who theme.
 * 15 April - 16 April - AUDIO: The Boy That Time Forgot was recorded.
 * 16 April - David Tennant met with new series producers Steven Moffat and Piers Wenger to discuss series 5 and whether he might reconsider his decision to leave. Tennant, who according to Russell T Davies had been "wobbling" on his departure, reaffirmed he would leave the role of the Tenth Doctor after the 2009 specials.
 * 21 April - 22 April - AUDIO: The Destroyer of Delights was recorded.

May

 * May - The CBC announced it would air Series 4 of Doctor Who beginning in September, but would not broadcast the second series of Torchwood.
 * 1 May - Still in the midst of shooting The Next Doctor, David Tennant refilmed the now-Cyberman-free closing scene of Journey's End.
 * 3 May - Production of series 4 officially concluded with the filming of the mini-episode Music of the Spheres.
 * 19 May - Cast readthrough for The Last Sontaran and The Mark of the Berserker took place.
 * 21 May - The BBC formally announced Russell T Davies would step down as executive producer of Doctor Who in 2009, to be succeeded by Steven Moffat, approximately twenty months after Davies first approached Moffat with the idea (per The Writer's Tale).
 * 22 May - Plans for Freema Agyeman to return as Martha Jones in the planned third series of Torchwood were derailed when Agyeman was signed to co-star in Law & Order: UK for ITV. (REF: Doctor Who: The Writer's Tale - The Final Chapter)
 * Late May - The BBC released a new television trailer promoting the final episodes of the fourth series.

June

 * 5 June - 6 June - AUDIO: The Ultimate Adventure was recorded.
 * Mid-June - American news media, including CNN, ran profiles of Billie Piper in conjunction with the debut of her series Secret Diary of a Call Girl in the US. Coincidentally this spike in US coverage coincided with the lead-up to her return to the series in Turn Left, although her involvement in Doctor Who was given only a passing mention.
 * 23 June - Cast readthrough for The Temptation of Sarah Jane Smith and Enemy of the Bane took place.
 * 24 June - Doctor Who won the Best International Series at the Thirty-fourth Annual Saturn Awards, an American entertainment awards program. The category was a new one introduced this year, and nominees included Torchwood, Steven Moffat's Jekyll and Life on Mars (which starred John "Mr Saxon" Simm).
 * Late June - The Canadian cable network Space announced it had obtained the Canadian broadcast rights to series 2 of Torchwood and would begin airing the series in August. Reportedly its timeslot would, in some parts of Canada, place it in direct competition with series 4 of Doctor Who when the CBC began airing it in September.
 * Late June - Several UK media reports indicated that David Tennant was in negotiations to return to Doctor Who for the 2010 series, but no official announcement was forthcoming (leading to additional speculation in the wake of the cliffhanger of The Stolen Earth a few weeks later), although it was known that he was to appear in the 2008 Christmas special, as photos of him shooting the special had leaked to the press months earlier.

July

 * Early July - The week between the cliffhanger ending of The Stolen Earth and the broadcast of Journey's End was marked by some of the most intense media attention Doctor Who has ever seen, especially given the uncertainty over whether David Tennant would remain with the series.
 * 7 July - The Daily Mail reported that more than 2,500 people actually attempted to phone the Doctor's phone number as shown in The Stolen Earth, in hopes of hearing a special recorded message, but the number was in fact non-functional.
 * 11 July - The Telegraph reported on rumours of David Tennant stepping down from the role of the Doctor, with David Morrissey, John Simm, and Robert Carlyle cited as the book-maker's favourites to replace him, despite Morrissey scheduled to guest star in the 2008 Christmas special and Simm having already played the Master in Season 3. Julie Gardner confirmed in the article that Tennant had made his decision as to whether he would stay on for the 2010 season, but she confirmed he would appear in all of the special episodes scheduled for 2009. Despite this, wildcat Internet rumours persisted that Morrissey would replace Tennant as early as the 2008 Christmas special, while some UK media reported Tennant had signed an agreement to stay with the series through Series 5 in 2010.
 * 12 July - Doctor Who swept the television categories at the second annual Constellation Awards, a Canadian award presented as part of the Polaris science fiction convention. David Tennant won for best Male Performance in a Science Fiction Television episode for his work on the two-parter TV : Human Nature/The Family of Blood; Carey Mulligan won the female equivalent for Blink; and the series itself won for Best Science Fiction Television Series of 2007. Doctor Who was eligible for these awards thanks to its co-production arrangement with the CBC.

September

 * September - Trailers for the second season of The Sarah Jane Adventures began appearing in cinemas in the UK, following on from the introduction of cinema trailers for the parent series. The trailer included specially shot footage of one of the characters addressing the audience.
 * September - GE Fabbri began test marketing a new multimedia publication called Doctor Who DVD Files in the northeast UK, in preparation for a British Isles roll-out of the publication beginning in January 2009.
 * 13 September - Recording for Hothouse took place at The Moat Studios.
 * 16 September - The Times began serialising excerpts from REF: Doctor Who: The Writer's Tale, including Russell T Davies' comment that Russell Tovey was his favourite to play the Eleventh Doctor; other media subsequently reported this.
 * 17 September - Russell T Davies and Benjamin Cook were interviewed on BBC Breakfast to promote REF: Doctor Who: The Writer's Tale.
 * 23 September - A BBC press release announced the title of the 2008 Christmas special, The Next Doctor, renewing fan speculation regarding David Tennant's future with the series into 2009.

October

 * October - In multiple interviews conducted in March and April of 2010, Matt Smith indicated he had been chosen to play the Eleventh Doctor "three months" before the official announcement was made in early January 2009. This meant the decision to cast him may have been made during October 2008 - possibly before David Tennant announced his departure.
 * 14 October - Russell T Davies received an e-mail proposing an idea for Torchwood: The Musical with members of ABBA doing the music. (REF: Doctor Who: The Writer's Tale - the Final Chapter)
 * 29 October - David Tennant and the BBC announced that Tennant would leave Doctor Who following production of the "gap season" specials in 2009. Tennant made the announcement on live TV when he accepted the National Television Award for Outstanding Drama Performance. The series also won Most Popular Drama. Tennant's announcement was made hours after The Guardian broke the news first on its website. As the winner of the NTA was not previously known, it was uncertain whether Tennant would be able to deliver his announcement on the air. The announcement was timed to occur during an intermission in his performance of Hamlet, and Tennant pre-recorded a version of it in the event the live transmission broke down. Earlier in the day, Russell T Davies and Benjamin Cook appeared on a TV broadcast discussing their book, REF: Doctor Who: The Writer's Tale, and managed to avoid discussing the yet-to-be-made announcement. (REF: Doctor Who: The Writer's Tale - The Final Chapter)
 * 29 October - Tennant's announcement sparked a period of intense fan and media speculation as to who would be chosen to portray the Eleventh Doctor. Speculated names ranged from well-known to obscure actors, and also included caucasian and black candidates, as well as a revival of speculation about a female actor being cast, an idea that dated back to the 1970s.

November

 * 25 November - The BBC announced that The Sarah Jane Adventures had been renewed for a third season, scheduled for broadcast in the fall of 2009.

December

 * December - Julie Gardner and other Doctor Who production team members travelled to Dubai, UAE, to scout locations for Planet of the Dead.
 * 10 December - Although the announcement wasn't made for several weeks, Russell T Davies was informed that Matt Smith had been cast as the Eleventh Doctor.
 * 24 December - A little-known actor named Matt Smith attended a secret photo shoot; it was so secret, in fact, that the hairstylist and photographer were not informed what it was for. Later, an image of the TARDIS was digitally added to the photos, which were issued on 3 January 2009 to announce Smith as the actor to play the Eleventh Doctor.