Scanning tunneling microscopy has been used to characterize the surface structure of the KHgC4 (stage 1) and KHgC8 (stage 2) graphite intercalation compounds. Images of the stage 1 and stage 2 materials exhibit a new commensurate 2×2 superlattice in addition to the centered hexagonal lattice observed in images of pristine graphite. Consideration of the intercalant layer structure and previous studies of stage 1 (MC8) and stage 2 (MC24) alkali metal graphite intercalation compounds (GICs) indicate that the 2×2 superlattice is due to a modulation of the surface carbon layer density of states by the periodic (2×2) potential of the potassium ions. In addition, a new orthorhombic superlattice, a=b=0.89 nm and ≪a-b≂89°, has been observed in images of the stage 1 KHgC4 material. Possible origins of this novel superstructure are discussed.