Supernova Progenitors Observed with HST

To understand the relevance of supernovae and to enable their use as probes of stellar evolution throughout time, it is necessary to determine their stellar origins. I describe the direct identification of supernova progenitors in existing pre-explosion images, particularly those obtained through serendipitous imaging of nearby galaxies by the Hubble Space Telescope. Establishing the astrometric coincidence of a supernova with its putative progenitor is straightforward. The interpretation of these results is more complicated and fraught with larger uncertainties. I describe the necessary ingredients for this interpretation. I comment on specific cases, particularly for core-collapse supernova progenitors, which are the only ones that have been detected to date. I also describe the need to revisit the supernova site, long after the supernova has faded, to confirm the progenitor identification through the star's disappearance and potentially to detect a putative binary companion that may have survived the explosion.