The Silhouettes were a race from the darkest parts of the universe.
The Silhouettes were energy parasites that were allergic to colour and light. They vaguely resembled large bats, with black skin and fur on their backs. They had glowing yellow eyes and large mouths with four sharp teeth. They had two claws, a long tail and a pair of bat-like wings each. They could grab ahold of other organisms and drain them of energy, turning them into dust. (COMIC: Sunscreen)
At some point in the 21st century, an asteroid full of Silhouettes travelled to Earth, where they attacked the Great Solar Shield, searching for sources of energy to feed on. They began to head for Earth, but the Doctor realised that they were allergic to colour and aligned the prismatic mirrors of the base to focus the light from the Sun into different wavelengths, creating a rainbow that scared them away. The Silhouettes travelled back where they came from. (COMIC: Sunscreen)