Abstract: In the next decade, new satellites and ground-based facilities will discover millions of supernovae (SNe) and large numbers of rare astrophysical transients, including exotic phenomena such as highly magnified stars and fast-radio bursts (FRBs). Individual, lensed stars at high redshift will allow direct study of massive stellar populations and dust at z~1-3, as well as provide a novel probe of the nature of dark matter. The James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope (WFIRST) should make it possible to study the deaths of stars as SNe to redshifts z~10–20, providing information about the first generation of stars and constraints on the expansion history. From the ground, the Large Synoptic Survey Telescope (LSST) will discover unusual, low-redshift analogs of high-redshift transients whose properties and host-galaxy environments can be studied in detail. Finally, FRBs are an intriguing new class of events which may originate from young magnetars. The sensitivity of the Square Kilometer Array (SKA) will make it possible to understand the potential connections between FRBs, super-luminous SNe, and magnetars.