D'Pau's species

D'Pau belonged to a species of short purple humanoids.

Once enslaved by a more advanced race that had conquered their homeworld, the species was liberated by Rose Tyler. Though they joined her empire of liberated worlds, behind her back, they saw an opportunity for revenge, enslaving their once masters. When the Eleventh Doctor showed Rose the flaws of her methods, he brought her to D'Pau's homeworld and showed her the results of her interference. (COMIC: Empire of the Wolf)