Mila

Mila was a human prisoner of the Daleks.

Biography
Mila was captured by the Daleks during one of their wars. The Daleks then experimented on her with bioengineered viruses in order to create a special virus that turned the beings it infects into Daleks. Due to these experiments, she lost most of her memories, but also gained unique abilities such as the ability to become invisible and non-corporeal. (BFA: Patient Zero)

Mila sneaked aboard the Doctor's TARDIS when he was being chased through time by the Daleks. (DW: The Chase)

Personality
to be added