The Waro were humanoid, but only the size of a human child. They were light and slender, which allowed them to fly with artificial wings. They had grey skin, sharp fangs, long ears and pointed features. They had yellowish-green blood and a very nasty odour. Though not especially strong, they could survive a large amount of damage.
The Waro had an overwhelming hatred of everything and an intense hunger for flesh. Using genetic and chemical modification, they could modify their emotions, so they hated everything that wasn't a Waro. Even so, they would eagerly tear apart another Waro if they were riled up or anxious for a fight. (PROSE: The Devil Goblins from Neptune)
The Waro had rocket-like spacecrafts, which would cluster together until they reached the atmosphere of a planet. These ships would give off radiation, which would sometimes be passed onto the Waro. These ships were designed so that the Waro riding was exposed to the elements.
The Waro used mechanical wings to allow themselves to fly. These wings were attached to their back on a backpack-like structure and were composed of metals and plastic. They were relatively primitive in design, relying on pulleys and joints, and the software used could be disrupted from a distance.
Early in their history, the Waro were constantly in a state of war, with empires of Waros rising and falling. There was little technological or societal change. Eventually, they were able to modify themselves so that instead of a hatred for each other, they hated everyone else.
In 1970, a probe was sent from Earth to Triton, and was picked up by the Waro. They were able to modify it and used it to telepathically contact Viscount Rose, directly sending their commands into his head. He was able to inform them about Earth, allowing them to plan their attack. The Waro sent forces to America, Russia and England in order to find the cobalt needed for their bombs. They deployed their forces to fool the humans, focusing their forces in Russia while they were trying to steal from England. When the Americans destroyed England's cobalt reserves, the Waro then focused their forces on the secret base in Roswell. They destroyed most of the American forces, but the Third Doctor and the Nedenah stopped them. (PROSE: The Devil Goblins from Neptune)