Photoemission spectroscopy shows that a very narrow peak and a broad distribution of density-of-states coexist near the Fermi level ( E F ) in K 3C 60, while the narrow peak at E F is not present in nonmetallic K 4C 60. This shows that K 4C 60, is a semiconductor with an energy gap at E F , contrary to the prediction from band structure calculations, and suggests that electron correlation is important in understanding the electronic structure of doped fullerenes, both metallic K 3C 60 and nonmetallic K 4C 60. The combination of photoemission, inverse photoemission and polarized oxygen-K-absorption in high T c oxide superconductors shows that the hole-doping results in a similar electronic structure to that of doped fullerenes with the coexistence of a very narrow peak and a broad distribution of density-of-states near E F . We discuss the similarities and differences between doped fullerenes and high- T c oxide superconductors based upon a comparison of their electronic structures.