At the European Space Agency (ESA) X-ray optics are being developed for future astrophysics and planetary missions. The cosmology mission XEUS requires very large effective area X-ray optics which high angular resolution. This implies a large aperture for a single telescope system, which will necessarily require assembly in space from basic mirror modules known as petals. The technology for the implementation of the Wolter-I design is based on the heritage of the XMM-Newton optics, but requires substantial further research and development. With 6 m2 effective area at 1 keV the XEUS optics is initially composed of 32 petals arranged in a circular aperture of 4.5m diameter, compatible with single Arian 5 launch into the XEUS orbit. Utilising the available infrastructure at the International Space Station (ISS) 96 additional petals, organised into 8 segments, are added to XEUS, increasing the effective area to 30 m2. Key aspects of the XEUS optics are therefore low-mass design, industrialisation of the production and ISS compatibility. As a potential optics for a remote sensing X-ray fluorescence spectrometer, extremely low mass Wolter-I optics are being developed. Based on Micro-Channel Plates (MCP), the mirror thickness can be dramatically reduced, making an accommodation on such missions as the Mercury orbiter of BeppiColombo possible. With a resolution of about 1 arcminute and compact construction, such imaging X-ray optics are well matched to modern Si or GaAs based detector arrays and will allow the mapping of the planetary surface in fluorescent X-ray light with unprecedented sensitivity.