Matt Smith’s regeneration contained a huge Doctor Who Easter egg that connected the franchise’s past and present in witty and poignant fashion. When Matt Smith departed the TARDIS at the end of 2013, he tied off various unresolved plot threads before he went, as Doctor Who revealed that the cracks in time, the Silence, Trenzalore, and other long-running mysteries had all been connected to the pending return of Gallifrey after the Time War. Eleven died trying to prevent a repeat of that conflict, and the Time Lords granted the Doctor a new regeneration cycle as a reward.

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