Example fluid valves having non-circular flow passageways are disclosed. An example fluid valve includes a body defining a fluid passageway between an inlet and an outlet, at least a portion of the fluid passageway between the inlet and the outlet has a generally non-circular cross-sectional shape when taken along a plane transverse to a direction of fluid flow, the cross-sectional shape includes a curved central axis, with outwardly curved end walls and curved lateral walls joining the curved end walls.