The Vardans are a race of aliens with the unusual ability to travel along broadcast wavelengths of any sort and materialize at the end. Until they are convinced that the environment at the other end of the wavelength is safe, they will not materialize themselves fully; instead, they appear as shimmering, metallic tentacled shapes - or, one might say, like wavy strips of tinfoil. In this form, the Vardans emit a crackling noise, and energy fired at them is reflected back upon the person wielding the weapon. The Vardans themselves use a weapon which fires a wide, silvery-white beam.
The Vardans' affinity for wavelengths allows them to read thoughts and even deep encephelographic patterns. They can also view people from a distance, presumably using the same technology, but this is inhibited by lead.
When the Vardans materialize fully, their actual forms are humanoid. They wear green uniforms with white edging and beige, visored helmets. They appear to be a militaristic society with large spacecraft.
The Vardans attempt to use the Doctor to help them take over the planet Gallifrey, but the Doctor uses it as a ruse to get the Vardans to materialize. Once they do, the Doctor is able to determine the co-ordinates of their home planet. He orders K-9 to activate the modulation rejection pattern, which sends the Vardans back to their home planet, which he plans to put into a time loop.
