Katya Dabrowksi was a mercenary spy in 1973 England.
She and her men knocked out Jess Collins and her family at their home in Brixton and brought them to an apartment in central London to meet the Master. When the Collins family were sent to a time locked dimension, she informed the Master that their artron signatures had been located and the portal to the dimension had stabilised. The Master forced the Doctor to be accompanied with Katya to the dimension, with the promise that he could be reunited with the Collins family. (COMIC: Doorway to Hell)