Monnay

 was a human living on a future colony planet of Earth where artificial trees were used to provide sustenance for the colonists. However, over time, their purpose was forgotten and the colonists began to sacrifice young women to the trees in belief that it would keep them safe, not knowing that they were actually stasis chambers. As a result, she was sacrificed by her mother, the forest elder, on one year's Bridal Day against her wishes.

One year later, the Thirteenth Doctor and Yasmin Khan discovered her but was unable to recover her like the rest of the sacrificed brides due to her arm breaching the tree when she was frozen in it. (COMIC: The Forest Bride)