The Mole People are a race of sapient moles which live in deep subterranean tunnels on planet Earth. There is also a group of Mole People living in the B-deck of R.U. Sirius, which Brewster rented to them. They once decided to leave B-deck and invade the "surface world", which is what they call the A-deck. Once getting there, however, they found it too bright and decided to retreat to B-deck.