Vorsun

Ms  was an alien operations managers at 3Sol.

In the 21st century, she tried to arrange the murder of Tyler Steele by posing as an anonymous source "Deep Throat" within the Cardiff city council. After both attempts failed, Tyler managed to find and confront her in a 3Sol office in person. Unable to call the security due to his WiFi jammer, she pulled up a gun and tried to kill him herself. Jack Harkness came to the rescue. In order to get them out of the filing cabinet they locked themselves up, Vorsun threatened to start killing her human staff and began fulfilling the threat. This forced Jack to surrender. Not knowing anything about Torchwood or Jack's immortality, Vorsun thought that she shot him dead, allowing him to ambush and kill her. (AUDIO: Changes Everything)

Behind the scenes
"Deep Throat" is an allusion to the involved in Watergate.