The Doctor From Gallifrey 

These have been confirmed but the episodes they happen in are completely unknown:

• Samuel Anderson will play Danny Pink, a teacher at Cole Hill School. It is thought he will become a new companion although this is unconfirmed, as is which episode he first appears in. 
• His character will also have a little sister, played by Ellis George.
  
• Singer songwriter Foxes will guest star and sing in an episode.

This feature-length episode will see Peter Capaldi as the Doctor proper for the first time.

It will feature Madame Vastra, Jenny and Strax and looks to be set in Victorian times. The trio will use sonic devices as designed by Blue Peter viewers.

This is a historical episode and from filming looks to be Doctor Who does Robin Hood. 

Tom Riley guest stars (probably as Robin Hood) as does Ben Miller (probably as the Sheriff of Nottingham).

Stars Robert Goodman (Game of Thrones)

Keeley Hawes stars as villain Ms. Delphox (see image below). Also featuring Jonathan Bailey and Pippa Bennet-Warner. From the character's outfit we would assume this a contempoary episode, or at least one set in the near future. 

Guest stars include Nigel Betts and Jimmy Vee (as seen in The End of the World & Voyage of the Damned)

• This episode was largely filmed on Lanzarote and looks to be a sort of sequel to the 80s story "Planet of Fire".
  
• Guest stars include Hermione Norris and Tony Osoba.
  

Frank Skinner will guest star in the episode.

Filming has seen actors Christopher Fairbank, Jovian Wade and Matt Bardock filming with Jenna Coleman. These scenes look to be contemporary but it is not confirmed they are from this episode.

• Michelle Gomez will guest star in this episode.
  
• The cybermen return!
• Jemma Redgrave and Ingrid Oliver return as Kate Stewart and Osgood.