“Timey wimey” doesn’t even begin to describe the Season 2 finale of Doctor Who. “The Reality War” brought the season’s long-running mystery — the Earth mysteriously being destroyed suddenly on May 24, 2025 — to its conclusion, but introduced a last-minute twist that saw the end of Ncuti Gatwa’s 15th Doctor, and the return of a very familiar face. But what does it all mean? Is the 15th Doctor really gone? Is the 16th Doctor really who she seems to be? Let’s dig into the wild, twisty ending of “The Reality War.”
Spoilers ahead for Doctor Who’s “The Reality War.”
Doctor Who “The Reality War” Ending Explained
The crux of the episode’s late climax, and the reason for the 15th Doctor’s regeneration, is the existence of Poppy.
“The Reality War” picks up with “Wish World’s” very literal cliffhanger by having the Doctor saved from his fall by Anita (Steph de Whalley), the hotel receptionist with whom the Doctor spent a whole year during the 2024 Christmas special. But Anita’s gotten a promotion to be the manager of the Time Hotel, which gives her access to a key that can open a door to any time. The time of May 24, 2025, however, is causing the Time Hotel to spasm, as the fate of Earth on this day puts the Hotel and its entire structure at risk of collapse. With Anita’s help, the Doctor breaks UNIT out of their Wish World-induced haze, and brings Belinda and their daughter Poppy back to the UNIT headquarters to wage war against the Rani (Archie Panjabi), Mrs. Flood aka also the Rani (Anita Dobson), and Conrad (Jonah Hauer-King).
The Rani’s plan, it turns out, is to bring Omega back to create a new Gallifrey — and she needs him to create the blueprint for a new Time Lord race, as the Master’s destruction of Gallifrey and genocide of its people left the surviving Time Lords (aka the Rani and the Doctor) infertile. Though the existence of Poppy throws a wrench in this whole explanation and scheme, the Doctor points out, as she shouldn’t be able to be created from his DNA. But she is real, and he and Belinda (Varada Sethu) are determined to make sure she will exist after the Wish World is destroyed, with the Doctor tasking Susan Triad (Susan Twist) with building a Zero Room in which Belinda and Poppy can be kept safe from the disintegrating reality.
And when the Rani and Omega are defeated by the Doctor (at alarming speed, thanks to a giant, zombified Omega eating Rani and the Doctor’s conveniently-placed Vindicator), their plan seems to have worked: they open the Zero Room, and out steps Belinda with a still-real Poppy. But when the Doctor returns with Belinda, Poppy, and Ruby (Millie Gibson) to the TARDIS, Ruby notices something odd happen: Poppy disappears, and the Doctor and Belinda don’t seem to remember her. When she tearfully pleads with the Doctor to save Poppy — who appears to have been a victim of “time shifting by one degree” — the Doctor jumps into the TARDIS with plans to use his regeneration energy to punch a hole into the time vortex and shift reality into its proper place. That’s when the first familiar face pops up.
Jodie Whittaker makes a brief cameo as the 13th Doctor, to warn the 15th Doctor about the dangers of punching a hole in the time vortex.
Jodie Whittaker’s 13th Doctor appears in the TARDIS, thanks to a “schism in time” caused by reality snapping back in place after the disintegration of the Wish World. She warns the 15th Doctor not to use his regeneration energy, as it could destroy the time vortex and all of reality — but concedes quickly as he tells her of the life at stake. (Side note: Whittaker has never been better than in these brief minutes written by Russell T Davies, one wishes her dialogue was as good as this in her era.) She heads off to not confess her love to Yaz, and the 15th Doctor prepares to blow a hole in the time vortex.
Suddenly, he wakes in the backyard of Belinda’s home and learns that Poppy is not his daughter, but only Belinda’s — a few inserted scenes of Belinda talking about Poppy throughout their adventures reveal that she had a daughter all along — and that’s why she was so desperate to get home. Happy that Belinda is reunited with the daughter she was desperate to return to, the Doctor heads off to finish his regeneration... and that’s when the biggest twist of the episode happens.
Billie Piper as the 16th Doctor?
The 15th Doctor regenerates at the end of this episode, with his face bursting into light and turning into... Billie Piper’s. “Oh, hello!” she says as she recognizes her new face.
That’s right, the actress who played the 9th (Christopher Eccleston) and 10th Doctor’s (David Tennant) companion, Rose Tyler, is back but as the Doctor. And yes, that means that Ncuti Gatwa’s 15th Doctor is gone: Gatwa confirms in this behind-the-scenes video that his era as the Doctor is over. It feels like a shame that his era ends after two seasons (making his run as the Doctor one of the shortest in the history of the show), especially after the 15th Doctor finally felt like he was coming into his own with Season 2. But we’re given little time to grieve his departure, with the reveal of the next Doctor — or is she?
Billie Piper as Rose Tyler.
But is Billie Piper really the 16th Doctor? Tinfoil hat theory time: In the credits, we see “Introducing Billie Piper,” but notably not “as the Doctor.” Could there still be ripple effects left from the reality shift caused by the disintegration of the Wish World? Is this another “glitch,” as UNIT calls the handful of other discrepancies? Or maybe she’s playing “Bad Wolf,” as she did in the 50th anniversary special, “The Day of the Doctor”? And does this mean Russell T Davies is building up to a very awkward reunion between Tennant’s 14th Doctor and Piper’s Doctor?
Who knows if we will find out soon, as Doctor Who’s future on Disney+ remains unknown. The only thing confirmed to be coming next in the Whoniverse in the The War Between the Land and the Sea spinoff, but it’s clear that the main show is building up to something big again. Or maybe it’s just another nostalgia ploy to keep the show afloat. At the very least, Doctor Who does what it does best: it leaves us bewildered, and oddly emotional, but always wanting more.
