We review off-axis telescope concepts that use unobstructed pupils. Built and prospective telescopes for ground and space astronomy will be presented and discussed. Such concepts offer great advantages in terms of emissivity, throughput, diffraction- limited energy concentration and higher dynamic range. The coronagraphic performance of off-axis telescopes will enable instruments, which are starving for higher dynamic range, for example, those devoted to faint companion detection and solar studies. Smaller telescopes like SOLAR-C (IfA/Haleakala Observatory), and the New Solar Telescope (NST/NJIT/ Big Bear Observatory) are operational and are test beds for the Advanced Technology Solar Telescope (ATST Project) for which site construction is beginning on Haleakala.