Vorsun

Miss Vorsun was a Sorvix and an operations manager at 3Sol. Aware of Tyler Steele's investigations into terrorism in Cardiff, she contacted him online using the name "Deep Throat" and lured him to the Refugee Crisis Centre shortly before it was bombed.

Tracing her IP address, Tyler tracked down and confronted Vorsun. Unable to call security with her panic button due to his Wi-Fi jammer, she drew a gun and attempted to kill him and Jack Harkness before they hid in a stationery cupboard, after which she took her human colleagues hostage and began shooting them one by one. When Jack emerged, she shot and killed him, with him doing the same to her once he resurrected. In death, she lost her human form. (AUDIO: Changes Everything)

Behind the scenes
"Deep Throat" comes from the involved in Watergate.