Mercy Hartigan

Mercy Hartigan also known as Miss Hartigan was a human agent of the Cybermen, she assisted them in their attempt to conquer Victorian Britain and ultimately the world.

History
Miss Hartigan was matron of the St Josephs Workhouse (A job for which she showed great dislike for). A few weeks prior to Christmas 1851 she met the Cybermen and agreed to help them achieve their goals in return for the promise that she would be heralded when their plan came to effect. She was also protected by a guard of Cybershades who protected her and drove her horse and coach.

When the Reverend Fairchild was killed she went to his funeral and set the Cybermen on the mourners, capturing the workhouse owners and killing the rest. The survivors were fitted with earpieces and told to bring their children to the Cybermen's base of operations.

They led children to a factory by the docks and made them work the machinery to generate electricity so that the CyberKing would rise. Miss Hartigan killed the workhouse owners and the Cyber-Leader decided to convert her into the CyberKing. She realised they had been planning to betray her the whole time and refused to be converted but was forced into it.

However once converted Miss Hartigan's superior mind gained control over the Cybermen's technology and not only managed to kill the Cyber-leader but also assumed leadership over the others. Shortly after this the Cyberking rose out of the Thames and attacked London with her acting as the 'brain' of the vessel.

The Doctor then used a device made from Infostamps to break the link between her and the Cybermen. She then saw what she had become and overcome with remorse destroyed both herself and the Cybermen. (DW: The Next Doctor)

Trivia

 * During the podcast for the Next Doctor Russel T Davies the writer of the episode confirmed that Miss Hartigan is a victim of sexual abuse and that that is why she sexualises every conversation and scenario she is in. This also explains her cruel and sadistic attitude toward men. However Davies felt that especially for a Christmas special this aspect of her would only be lightly touched upon for the safety of a young viewing audience.