Dee

Dee was a freedom fighter in an alternate Earth.

After getting William Hastings to take her to the Turing Shroud room in the Tower of London, she killed him. When Frank was revealed as a double agent, she killed him as well. Dee was then shot to death by Hannah Baxter. (PROSE: The Domino Effect)

Behind the scenes
It is implied that the ponytailed Dee, who used homemade explosives and terms like "toerag", was that timeline's version of Ace.