Linktons were a sentient humanoid species from Linktos, a planet in a galaxy other than Mutter's Spiral. They once tried to invade Victorian era London through the use of an advanced teleportation technology powered by gold.
When the Linktons tried to teleport their way to Earth, they were stopped by the Fourth Doctor and Leela, who smashed their teleportation equipment. This caused a fire, which melted those few Linktons who had successfully travelled to Earth. (PROSE: The Living Wax)