Duvals are a creature in Florida and Texas in 2174. They are the only creature that terrorizes the settlements in The Guilt of War. They originate from the Jacksonville Ruins, where on the day the bombs fell horse riders started joining with there horses and going mad. They ran into the St. Johns river, where they also combined with manatees.

They apparently have spread throughout all of North America, as in The Pride of War, they inhabit the remains of Armarillo and Gulf Row. They are in a much smaller amount in Texas than they are in Florida.