A mutated human who guides heighliners through foldspace using spice-induced prescience. Navigators consumed such vast quantities of melange that their bodies were physically transformed, eventually requiring sealed tanks of spice gas to survive. Their limited prescience allowed them to foresee safe paths through the mathematics of foldspace, replacing the banned computers that once performed interstellar navigation. A Navigator's abilities made the Spacing Guild's transport monopoly possible, but also made the Guild utterly dependent on the continued supply of melange from Arrakis.