Goodthing
Goodthing was a human colonist of the far future who lived in the colony planet Gliese 581 D.
She was among the set-up team who were awoken from stasis to make sure the city was functioning properly. At some point, she discovered her mother, Hopeful, Sunshine, Eliza and several other colonists had been killed by the Vardies but she realised that it was because they showed negative emotions such as grief. She managed to force herself to keep smiling to avoid the same fate.
Later she called her colleague Kezzia who at the time was overseeing pollination of the wheat fields by Vardies. Goodthing warned her to stay outside the city but Kezzia didn't listen. Once she returned, Goodthing informed her of the deaths but desperately told her to smile, only for Kezzia to be seized by an Emojibot and ripped apart by a swarm of Vardies.
The Twelfth Doctor and Bill later came across her remains, along with the bones of the other colonists who had been turned into fertiliser. (TV: Smile)