There is a big hint or reveal in the latest Doctor Who Season 8 Trailer..
This is the newly released trailer. Watch it! “I see into your soul, Doctor”
“I see into your soul Doctor,” a nasty voice bellows. “I see beauty, divinity, hatred!
Apparently some big villain is returning. It might be be a Dalek, or
Davros, the Emperor Dalek or Dalek Caan!
Source: Digital Spy