Doctor Who: EVERY NuWho Villain And Monster Ranked Worst To Best

Appears in: The Girl Who Died, The Woman Who Lived, Face the Raven, Hell Bent.

What happened to the young Viking who made puppets and died heroically saving her village? Well, with the help of a reprogrammed Mire medical capsule, the Doctor resurrected Ashildr... forever, and he was right to worry about the possible ramifications.

Immortality made Ashildr/Me (Maisie Williams) thoroughly miserable as she continually saw loved ones die and refused to have anymore children to avoid the pain and sorrow of losing them again. Given the many lives she lived, Ashildr forgot large swathes of her experiences: reading her own journals "out of curiosity", so inured she had become to life in general.

However the Doctor felt the full force of these ramifications in Face the Raven, where Ashildr - now calling herself Mayor Me - colluded with Rassilon to set a trap that led to the Doctor being teleported into his confession dial, imprisoning him for 4.5 billion years! The whole plot also brought about Clara's death (yes and no on that one really), albeit inadvertently. Now they were enemies, with Ashildr chillingly told to keep out of his way.

But they say time heals all wounds, to the extent that Ashildr and the Doctor's next encounter was at the end of time itself, having a good old chinwag about who or what the Hybrid was/is (although Clara had returned at this point and perhaps punching away at an Azbantium wall for billions of years helped release his anger).

The last we saw of Ashildr was setting off on adventures with Clara in the American diner TARDIS, so hopefully she's living her best life now.