Saibra

 was a mutant human who would replicate a person when touching any part of their organic matter. She also wore a hologram shell to help replicate clothing.

Early life
Saibra was born with a mutant gene which caused her to shapeshift into any person she came into contact with. She came to view her power as a curse, as it caused people to distrust her since she would “look back at them out of their own eyes.” Saibra was thus alone even into adulthood. (TV: Time Heist)

Robbing the Bank of Karabraxos
As she was unable to control her ability, she helped the Twelfth Doctor rob the Bank of Karabraxos in order to gain a gene suppressant which would remove her powers. During the mission, she briefly impersonated Clara Oswald to demonstrate her power and impersonated a businessman named Mr Porrima to facilitate entering the bank, before copying a security guard to rescue the Doctor and Clara after they were captured. After the mission was successfully completed, Saibra shared a takeaway with the others before being returned to her own time and place, having used the gene suppressant. (TV: Time Heist)

Abilities
Due to a mutant gene in her physiology, Saibra had the ability to mimic the appearance of any life form she came into physical contact with right down to their DNA by replicating living cells. She wore a hologram shell to replicate clothing. The image could be maintained for as long as she needed. However, she had no control over her power and usually wore gloves to suppress it.

Due to “having had many faces”, Saibra was skilled at reading people and could easily see if someone was lying. (TV: Time Heist)