Ncuti Gatwa's time as the Fifteenth Doctor has come to a shocking end in the Doctor Who season 15 finale, regenerating into a very familiar face. There have long been rumors that Gatwa was due to step out after Doctor Who season 15, and it seems they were correct. The season finale, "The Reality War," ends with the Doctor sacrificing his life to restore his daughter Poppy into the timeline.

The experience leads to a shock regeneration, with the Doctor transformed into a very familiar face. Billie Piper - best known for playing former companion Rose Tyler - is now the Sixteenth Doctor. It's not the first time the Doctor has taken on a face we've seen before; that most famously happened with Peter Capaldi. But this is undoubtedly the most spectacular, because Piper is already so closely associated with Doctor Who.

Why Has Doctor Who Brought Back Billie Piper As The Sixteenth Doctor?

A Surprising Choice For A Regeneration

There have been rumors of Gatwa's regeneration for months now. His casting as the Fifteenth Doctor was a coup for the show, but Gatwa's star has risen since then, and he was known to be playing at the West End later this year - making it doubtful he would continue as the Doctor. The BBC's partnership with Disney+ made this star casting possible, and the future of that deal is uncertain, explaining the regeneration. The show gives Gatwa a wonderfully human reason for regenerating, with smaller, more intimate stakes leading to an emotional final scene.

But why has Billie Piper returned to play the Doctor? Piper played Rose Piper in the Christopher Eccleston and (first) David Tennant era, and returned in cosmic form in the Doctor Who 50th anniversary special. Modern Doctor Who is clearly unafraid to embrace nostalgia, and Piper's return is certain to appeal to older fans. She's a phenomenal actress, she absolutely loves Doctor Who, and she knows exactly what it means to embody the Time Lord.

Our Take On Billie Piper's Doctor Who Return

A Big Gamble For Doctor Who

Many fans were doubtful about Piper's casting when she was first announced for the role of Rose Piper, but she swiftly proved them wrong. That means any doubters should really be very careful about underestimating the actress; she understands the franchise better than most, and she's played alongside multiple Doctors - some of the best. Should Doctor Who be renewed for season 16, she'll work hard to make the role her own.

At the same time, though, Piper's return does seem symbolic. The first Davies era avoided indulging in nostalgia and fan-service; the Time War was really a smart way of wiping the slate clean. In contrast, the latest era - also helmed by Davies - has depended heavily on deep-cut lore. Piper's return to Doctor Who feels as though it embodies this difference - and only time will tell whether that proves to be a good call.