The Bodach were incorporeal creatures who fed on dreams.
The Bodach fed on the energy produced by a mind when dreaming. They could emit psychic energy which would cause nightmares, allowing them to feed. This psychic energy could be blocked by tin foil hats. As the Bodach had no body, they were forced to control these sleeping people, using them to interact with their surroundings. (TV: Dream-Eaters)
The Bodach were known to the Celtic people, who believed they were evil spirits. At some point, an Obelisk was made with two crystal eyes. With these crystals, the Bodach would be able to send the whole world to sleep and feed on their dreams. In unknown circumstances, this did not come to pass, and instead the obelisk was buried outside what would be London.
In 2050, the site was dug up and one of the eyes was removed and sent to Professor Alistair Gryffen for study. This attracted the attention of the Bodach, who sent London to sleep, and possessed June Turner to get the eye back. As K9 was a robot and unaffected, he was able to wake up Starkey, Darius and Jorjie. Starkey was able to wake up Professor Gryffen. Using tin foil hats to protect themselves, they tried to stop the Bodach from taking back the crystal. Unfortunately, Darius neglected to wear his hat, allowing the Bodach to send him to sleep and control him, forcing him into giving up eye. K9 tried to stop the eye from being reinserted and rammed the obelisk, but was repelled by a force field. Jorjie used the Bodach's mask to enter June's dreams and woke her up. June was then able to remove the eye, deactivating the force field and allowing K9 to destroy the obelisk. (TV: Dream-Eaters)