The Wire

The Wire was a criminal from the planet Hermethica.

Biography
The Wire was sentenced to death and executed by its people, but it managed to preserve itself as an energy being that escaped to Earth in 1953, through the communications device of one of its executioners, who was illegally recording the execution. (REF: Doctor Who: Creatures and Demons, Doctor Who: The Ultimate Monster Guide)

It concealed itself in television signals, transferring itself from set to set. It fed off the mental signals of the brains of humans, paralysing them and then sucking out their energy with electrical tendrils. This process would leave the victim mindless, as well as faceless. The victim's consciousness was retained intact, as seen when The Wire showed the Doctor a sampling of its victims on the televisions in Magpie's shop. The Wire used the image of a female BBC continuity announcer to communicate with the outside world. It hoped to use this energy to manifest itself in its corporeal form once more.

The Wire stole the face of Mr Magpie, who owned an electrical shop, and gave it back to him, giving him plans for then-future technologies (such as a portable television small enough to carry in one hand) and promising freedom to him after the completion of its simple two-phase plan: First, have Magpie sell cheap television sets all over North London so it could feed. Second, have Magpie connect the Wire (inside the portable television) to the television transmission tower at Alexandra Palace on Queen Elizabeth II's coronation day, June 2nd, 1953. Connected to the tower, the Wire could both transmit itself to the estimated three million viewers watching in the vicinity and transmit back energy it could use to re-constitute its corporeal body.

However, the Tenth Doctor was able to trap the Wire on a Betamax tape using a makeshift video recorder. The Wire's victims were then restored to normality. The Doctor seemed confident that the Wire would remain trapped, but said that he would tape over it, just to be safe. (DW: The Idiot's Lantern)

The Wire may have returned in the Beetee incident. (REF: Doctor Who: Creatures and Demons)