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.
Biology
Linktons were humanoid, though not much was known about their physiology. They were known to have three fingers on each hand, and to be made mainly of wax. They were thus highly vulnerable to fire.
History
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.