Stars, star formation, stellar populations and planets.- Hot Massive Stars: The Impact of HST.- HST Spectroscopy of the Hottest White Dwarfs.- Key Abundance Tracers in the UV: From the Lightest to the Heaviest.- UV Spectroscopy of Metal-Poor Massive Stars in the Small Magellanic Cloud.- Star Formation Histories of Resolved Galaxies.- HST's View of the Youngest Massive Stars in the Magellanic Clouds.- Planetary Nebulae and Their Central Stars in the...