Series 1 (Relative Dimensions)

Series 1 is the first series of Relative Dimensions.

Production
The first series of Relative Dimensions was announced by the BBC as a new spinoff of Doctor Who intended to combine elements from the 50+ years of Doctor Who history in a single programme. Several past Who actors, including Billie Piper, were approached for the project. Billie Piper was the first to announce her role in the series, confirming that she would be recurring in the first series.

It was announced that Matt Smith would be reprising his role as the Eleventh Doctor for the series, along with Doctor Who series 10 companion Bill Potts as portrayed by Pearl Mackie. Additionally, showrunner Mark Gatiss revealed the first three episode titles: The Doctor, Beauty and the Beast, and Turn the Page, as well as their key crew.

It was announced that David Tennant would be reprising his roles as the Tenth Doctor and the Meta-Crisis Tenth Doctor for the series, however, not as the main Doctor. It was also confirmed that Stephanie Hyam would be appearing as Heather.

The BBC revealed more details for the series beforehand, as well as the surprising appearances of Alex Kingston as River Song and John Simm as the Master.

It was confirmed that the main enemies would be the Cybermen, Daleks, and the Master, and that in the ninth episode, Leave, Karen Gillan and Arthur Darvill would reprise their roles as Amy Pond and Rory Williams, respectively.

Confirmed

 * More "connected" episodes.
 * For example, episode 4 is a sequel to episode 1 and leads directly to episode 5.
 * Rose Tyler and Bill Potts being required to save the Doctor.

Rumoured

 * The return of the Silence.
 * Based upon the titles for episodes 7 and 8, The Fourth Knock and Extermination of the Doctor, respectively, the Master will engage in an alliance with the Daleks. This may tie in to the episode 1/4/5 storyline.

Cast

 * The Doctor - Matt Smith
 * Rose Tyler - Billie Piper
 * Bill Potts - Pearl Mackie

Recurring

 * The Doctor  and his  meta-crisis  - David Tennant
 * Heather - Stephanie Hyam
 * River Song - Alex Kingston
 * The Master - John Simm
 * Amy Pond - Karen Gillan
 * Rory Williams - Arthur Darvill

Guest

 * Cadania - Lisa Bowerman

Aliens and enemies

 * Cybermen
 * Daleks
 * The Master