The Giggle saw the Fourteenth Doctor face one of his oldest and most terrifying enemies, the Toymaker, originally played by Michael Gough and this time brought to life by Neil Patrick Harris.
With the world driven mad, the Toymaker also taunted the Doctor and Donna Noble (Catherine Tate), bombarding them with tricks and games.
In a shocking twist, the Fourteenth Doctor (Tennant) regenerated at the hands of the Toymaker but instead he 'bi-generated' and two Doctors were left - the Fourteenth and the new Fifteenth Doctor (Ncuti Gatwa).
Together, the two Doctors beat the Toymaker before having an emotional discussion of past losses with Donna and Mel Bush (Bonnie Langford).
Afterwards, the Fifteenth decided to go travelling in the TARDIS while the Fourteenth chose to stay behind with Donna and her family.
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However, with the remainder of their power from defeating the Toymaker, the Fifteenth claimed their prize: a duplicate TARDIS.
As Fourteen and Fifteen said goodbye, we later saw the Fourteenth Doctor enjoying a meal with Donna, Mel, Rose Noble (Yasmin Finney), Shaun Temple (Karl Collins) and Sylvia Noble (Jacqueline King).
While the Fourteenth can still go on adventures - and likely will with an eager Rose - he plans to enjoy some downtime for now.
Now, fans have taken to social media to react to the highly emotional scenes which felt like some wonderful wish fulfillment.
One fan penned on X, formerly known as Twitter: "14th DOCTOR HAS A FAMILY! CALLING DONNA HIS SISTER AND BEST FRIEND! ROSE HIS NIECE! WILF HIS GRANDAD! SYLVIA HIS WICKED STEP MUM! SO EMOTIONAL #DoctorWho".
A different viewer wrote on X: "Imagine going back and telling those of us watching him wipe her memory in series 4 it would end like this. I am fragile #DoctorWho"
Elsewhere, on X, one fan was less impressed with the bi-generation twist, penning: "Already feel like bigeneration is something that’s never gonna sit right with me. #DoctorWho".
Finally, one Doctor Who viewer concluded on X: "14’s end was really beautiful. “I’ve never been so happy in my life.” I have some issues with bigeneration but I’m really glad to see a happy ending. #DoctorWho".
The episode marked the final instalment in the 60th anniversary specials, which saw Tennant and Tate return together after 15 years.
It also introduced us to Ncuti Gatwa's Fifteenth Doctor for the very first time, with his first full episode to air on Christmas Day.
Doctor Who will return for The Church on Ruby Road on BBC One at 5:55pm on Christmas Day.
Previous episodes are available on BBC iPlayer and on BritBox – you can sign up for a 7-day free trial here.
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