Bio: Gorolith was the controller of the observer units, like Beholder Panoquai, and de facto captain of the Ophidius. He was self-described as the "supreme creation of the Ophidians", a bio-mechanical entity working to save the race that created him.
He was in charge of engineering what was essentially a competition. By using observer units, he would take notes on various species in order to find the one that was the hardiest and most adaptable. Then, he would use a race of body stealers to transfer his dying race, the Ophidians, into that species.
The Eighth Doctor and Izzy were, unsurprisingly, opposed to this plan.