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!

Ncuti Gatwa regenerated into Billie Piper in the series finale of Doctor Who on Saturday night. He left the role after playing the iconic character for two series. Piper, who previously played the Doctor's assistant, Rose Tyler, said the opportunity to "step back on that Tardis one more time was just something I couldn't refuse".

Piper, now 42, originally played companion Rose Tyler in 2005 alongside Christopher Eccleston’s Ninth Doctor. She went on to appear opposite David Tennant and was later revealed to be the mythical "Bad Wolf" - a mysterious, universe-shaping figure. Now, she’s taken the role full circle by stepping into the shoes of the Doctor herself.