Monoid

Monoids were a humanoid species that travelled on the Ark with the last of the Humans.

Biology
Monoids were humanoid in shape but had green fur, one eye and hair that stretched down their face. They were all mutes, communicating through sign-language. Monoids ingested food through holes in their neck. Instead of names, all the Monoids had numbers based on rank. (DW: The Ark)

History
In the 101st century, one of the shows in New Earth Republic was Confessions of a Monoid. (PDA: Synthespians™)

The Monoids arrived on Earth long before the Ark went into space. Their own planet was dying, and they offered their services in return for a place on the Ark. The Humans accepted and welcomed them on the trip. While travelling, the Monoids fulfilled a near-slave role, carrying out menial tasks for the Humans.

After several hundred years of travelling, the Ark neared its destination, Refusis II. The Monoids staged a revolution and made the Humans their slaves. They then completed the Humans' statue by adorning it with a Monoid head instead of the intended Human one. In this they planted a bomb, to be detonated when they abandoned the Ark and left the Humans behind.

After Two did not complete communications from the surface of Refusis II, the Monoids began a full scale landing. However, mutiny resulted in the deaths of several Monoids as fighting ensued. The bomb was ejected into space by the Humans, saving the Ark. The surviving Monoids then returned aboard. The Refusians agreed to welcome both species to their planet if they were to become friends. Both agreed. (DW: The Ark)

Other References

 * Monoids could be found at the Pridka Dream Centre. (NA: Infinite Requiem)
 * The Tenth Doctor compared the Human Badgers and the Ood to the Monoids, all three being slave races. (NSA: The Pirate Loop)