Rhodian

The Rhodians were a humanoid race on Rhodia. They were at war against the Quill.

Biology
to be added

Culture
The Rhodians were a cultured, learned society. Homosexuality was more accepted than on 21st century Earth. (TV: For Tonight We Might Die)

They had what Miss Quill considered a cruel punishment, but Prince Charlie considered just. This punishment was carried out after they defeated the Quill in battle. They released a creature into the brain called an arn. Once it dug itself in with its poisonous claws, the arn would telepathically link the host to a particular Rhodian, and force them to become their effective slave. If they were to break a rule, or fail to protect their master, the arn would kill them. (TV: For Tonight We Might Die)

History
According to Miss Quill, the Rhodians ate up all the planet's resources, including that of the Quill. They tried to help the Quill, but in the process made them so dependent that they could never recover. (TV: For Tonight We Might Die)

The two species were eventually at war with each other. The Rhodians won.

While they were busy fighting amongst themselves, the Shadow Kin arrived, and killed everyone, Quill and Rhodian alike. All but one of the Rhodians were destroyed by the Shadow Kin: Charlie, their prince, who was brought by the Twelfth Doctor to Coal Hill Academy. (TV: For Tonight We Might Die)