The Rodents of Unusual Size (known by the acronym R.O.U.S.) are vicious wolf-sized predatory rats native to the dreaded Fire Swamp, in the vicinity of Guilder. As no one who entered the swamp has actually survived it, the R.O.U.S. are considered nothing but the stuff of legends by some people.
- The Princess Bride, by William Goldman (1973)
- The Princess Bride (1987)