Welcome back to Doctor Who, Billie Piper! The British sci-fi series just shocked fans when, in the Season 2 finale, Ncuti Gatwa ‘s Doctor regenerated — and the Sixteenth Doctor appears to be played by none other than Piper!

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.

And, of course, the 14th Doctor was played by David Tennant who ended up reuniting with Donna Noble (Catherine Tate) where he continues to live now after Ncuti’s version bi-generated out of him (which could come to play in a later theory…)