Vastra

Vastra was a female Silurian warrior who was friends (and implied lover) with a human woman in Victorian London.

She was one of many people who owed the Doctor a debt. After eliminating Jack the Ripper, she was summoned by him to help in the mission to rescue Amy and her baby at Demon's Run. She and Jenny arrived at Demon's Run along with a army of Silurian soldiers, they both survived the battle with the Headless monks. She also knew a lot about Time Lords as she refers to regeneration, the Untempered Schism and the time vortex. (DW: A Good Man Goes to War)