Usurian

The Usurians are manipulative life forms native to the planet Usurius. They don't need to breathe and look like a small handful of green kelp in their natural form, although they belong to the fungus, not vegetable kingdom. They can assume the shape of a dwarfish humanoid as long as they constantly expose themselves to particle radiation. They are listed in Professor Thripsted's Flora and Fauna of the Universe as poisonous fungi.

Though they were originally a war-like race, this was inefficient and so they turned to commerce, creating the Company. Apparently very knowledgable, their databases contained information on Gallifrey (which they did not consider a viable market for their consumer products) and knew of the Doctor's previous acts of "economic subversion".

The Company moved the Humans of Earth to Mars after Earth became uninhabitable due to pollution. The Humans were nearly taxed to death. When Mars also became uninhabitable, they moved the humans to the city of Megropolis 3 on Pluto and set up six artificial suns. They drugged the humans with sedatives, exploited them and ruthlessly taxed them, under the leadership of the Collector. (DW: The Sun Makers)

Minor references
Legion had encountered the Usurian before and noted their obsession with business. (NA: Lucifer Rising)