Baggolt

The Baggolts were the robot servants of the Ethereals. They rebelled against their masters and tried to vaporise them, but only succeeding in turning them into living clouds. Five eketrons later, the First Doctor visited their world, restored the Ethereals' original bodies, and helped their leader, Mitzog, put an end to the Baggolt rebellion. (PROSE: The Cloud Exiles)