Gamma-Ray Bursts and Supernovae from massive stars are among the most powerful explosions in the universe. We work on fore front problems in stellar death astrophysics through extensive and panchromatic observations of various types of massive stellar explosions, as well as a growing class of exotic transients. With the goal of understanding their stellar progenitors and the explosion conditions that determine the fate of massive stars, we study both explosion properties and the stellar explosions' host environments and host galaxies. In addition, we are interested in excluding contaminants in high-z SN Ia searches for cosmology. Astrophysics is entering the Golden Age of innovative time-domain surveys that stand to revolutionize our understanding of the transient sky. We are part of the very successful Palomar Transient Factory (PTF, which finished as such in Dec 2012, and is now continuing as iPTF), as well as the large-scale Large Synoptic Survey Telescope (LSST) planned for around 2018 .