The Voice
From Tardis Wiki, the free Doctor Who reference
The Voice was on a recording of a self-help tape. It took over Captain Jack Harkness as a way to take over Torchwood Three using an innocent bystander to inhabit his body. Jack tried to fight back. It was defeated by the innocent bystander by shutting Jack's body. (AUDIO: Tropical Beach Sounds and Other Relaxing Seascapes #4)