Gråttite

The Gråttites were humanoid creatures from the planet Grått. (IDW: The Whispering Gallery)

Biology
Gråttites exhibited pale white skin with bright blue eyes. They were tall and thin, with long necks and elongated skulls. Their heads were completely bald. (IDW: The Whispering Gallery)

Society
The Gråttites lived in a society where emotion was banned due to the threat of the Mörkön, an Empathivore. Due to this, all the architecture and design on Grått was very drab. A police force existed solely to confront anyone who was showing any emotion. Anyone to do so was deported.

Upon death, a Gråttite's body would be buried in a graveyard and their portrait hung in the Whispering Gallery. The portrait would have the Gråttite's last stream of consciousness embedded within it. (IDW: The Whispering Gallery)

Clothing
Gråttites adorned themselves with jewellery including earrings, necklaces and headbands, often with jewels set in them. Some also wear elaborate make-up around the eyes. The majority of Gråttites wear long pale robes that reach to their feet, although the police wore more practical black jackets and trousers. (IDW: The Whispering Gallery)

Technology
Gråttites were reasonably advanced. They developed hover cars and flying machines capable of helping to erect a statue. They also possessed powerful sedatives capable of numbing both the mind and body, stopping the body from feeling any emotion.

They were also capable of creating a Data Ghost of a dying Gråttite's last thought. (IDW: The Whispering Gallery) This technology wasn't developed by humans until the 51st century. (DW: Silence in the Library/ Forest of the Dead)

History
The Gråttites used to exist happily. However, at some point an Empathivore came to the planet and fed off the negative emotion of the people. The more people that died by the Empathivore, the more grief that existed on the planet and hence the larger the Empathivore would become. Eventually, the Gråttites learned to control their emotions and be completely emotionless. This caused the Empathivore to shrink and go into a slumber.

Several generations later, the Empathivore had passed into myth and people began showing emotions again. When they began mourning loved ones, the Empathivore awoke again.

A few years later, the Tenth Doctor visited Grått and defeated the Empathivore, allowing the Gråttites to begin showing emotion again. (IDW: The Whispering Gallery)