Grey alien

The "Grey aliens" were a species at war with the Viperox during the 1940s and 1950s.

They were nicknamed by Cassie Rice.

Biology
The Grey aliens were short humanoids with blue-grey skin and large heads. Their large eyes had milky, star-like matter inside them instead of pupils. (TV: Dreamland)

Technology
The Grey aliens were thousands of years ahead of humanity during the 1950s. They had vaguely saucer-like spacecrafts. These were a burnished, red colour, with gill-like slits down the side. They were controlled by touch-activated panels. (TV: Dreamland, TV: Prisoner of the Judoon)

The Grey aliens had glowing spheres that could heal damage. Rivesh Mantilax also created a bioweapon that was locked to the DNA of the Viperox, allowing the weapon to destroy all the Viperox in existence. It was disguised as a ionic fusion bar and could only be activated by his DNA. (TV: Dreamland)

History
In the 1940s, the Grey aliens were on the brink of war with the Viperox. They sent an ambassador, Seruba Velak, to broker a treaty with the Viperox in 1947, but she was shot down by pirates and crashed on Earth. She was captured by the United States of America military and taken to Area 51. There, her ship was dismantled and reconstructed, though the humans were unable to fix it properly. Without her, the war began and the Grey Aliens began to lose. In order to try to salvage a victory, Rivesh Mantilax created a weapon that could destroy all the Viperox.

In 1948, Rivesh came to Earth to look for Seruba. He was being followed by the Viperox and was also shot down by the military, though Rivesh was saved by Night Eagle's tribe. He was adopted by them and protected by the androids sent to find him. When the Tenth Doctor was brought in to meet him, he was followed by Colonel Stark and his soldiers, allowing them to be captured. Though Rivesh was nearly reunited with Seruba, Rivesh was injured by the Viperox Azlok, meaning the bioweapon couldn't be activated. The Doctor and Seruba were forced to go into the Area 51 Vaults, where there was the healing device from her ship. They were able to find it and bring it back, healing Rivesh and allowing him to activate the weapon, which the Doctor modified to drive off the Viperox. Following this, Seruba and Rivesh left Earth. (TV: Dreamland)

The designs for Seruba's ship were kept within the vaults. Androvax used Mr Smith to steal these schematics and commanded the Nanoforms to recreate the ship. When Androvax was caught, Captain Tybo confiscated the ship and flew it off-planet. (TV: Prisoner of the Judoon)