The Moxx of Balhoon is a small, blue, goblin-like creature who sits on an antigravity chair because his atrophied legs are too small to carry his overweight body. He appeared in the Series 1 episode, The End of the World by Russell T Davies. His speech is terse and to the point, and he greets people by means of formal spitting. As detailed in the book Doctor Who: Monsters and Villains by Justin Richards, the servo-motor in the Moxx's chair must replace his bodily fluids every 20 minutes or he will start to sweat glaxic acid. He is apparently grateful if someone points this problem out and may even reward them with a coin of "solid blick," or a song, his favourite apparently being "Yap Cap Forward Bigga Toom Toom Toom". "People" with similar conditions to the Moxx include Ciths and Grames of Balhoon. It is unknown whether Moxx is an honorific (as in Duke of Edinburgh) or an identifier (as in Richard of York).

The Moxx represented the solicitors Jolco and Jolco. When the systems on Platform One were sabotaged, he was among those incinerated when the Sun's rays break through the protective exo-glass of the observation room.

Celestial Toyroom, the magazine of the Doctor Who Appreciation Society, reported that the Moxx will be appearing in Series 2. Which episode this will take place in is not known. The Moxx was portrayed by Jimmy Vee, who also played the pig "alien" in Aliens of London and the Graske in the interactive adventure Attack of the Graske.