Oh, hello.” Those two words, from the person Ncuti Gatwa‘s Doctor regenerated into in the Doctor Who Season 2 finale, kick off a slew of questions we now have. Because that person? Billie Piper, very recognizable to fans as Rose Tyler,

The season finale of Doctor Who, ‘The Reality War,’ was shocking for many reasons. However, the biggest surprise involved an appearance by actress Billie Piper, who played Ninth and Tenth Doctor companion Rose Tyler.

Doctor Who fans across the world were gagged on Saturday night when Billie Piper made an unexpected return to the franchise. After weeks of speculation about whether Ncuti Gatwa’s time as The Doctor was coming to an end in the not-too-distant future,