Terrain relief—the spatial configuration of Earth’s solid surface—constitutes the fundamental template upon which climatic, biotic and anthropogenic processes play out. Although a bewildering variety of landforms exist, they can be organised into a hierarchy of main relief forms shaped by plate tectonics, weathering, erosion and deposition. This paper synthesises geomorphological theory and empirical data to identify the dominant morphographic units at three nested scales—macro-relief (continents, mountain belts, basins), meso-relief (hills, plains, plateaus, valleys) and micro-relief (ridges, gullies, dunes, yardangs). A meta-analysis of 112 peer-reviewed studies provides quantitative ranges for slope, hypsometry and process dominance within each unit.