Rakghoul
these mutated, flesh-eating creatures lived in the Undercity, beneath the surface of the cityscape of the planet Taris, many millennia before the Battle of Yavin. It was believed that rakghouls were actually humans who had been infected with an unusual disease, a disease which they transmitted when they attacked other humans. Because the mutation from human to rakghoul was incredibly swift, many pathohistorians believed that the original infection had been bio-engineered by an ancient race, though this was never proven. No effort was made to eradicate the disease which created the rakghouls, as city officials claimed it eliminated the criminals and outcasts they were "too humane to exterminate." It was believed that the ancient Sith had an antidote to the rakghoul infection, but no record existed of its formula. Many rakghouls were simply mindless killing machines, but a few individuals - which came to be known as rakghoul fiends - were known to exhibit leardership abilities and could use weapons.