We consider the relation among collapsars, supernovae, X-ray flashes, and other possible off-axis phenomena, e.g., uv-transients. New three-dimensional calculations are presented of relativistic jet propagation and break out in a massive Wolf-Rayet star. The supernovae that accompany GRBs are novel and need not be standard candles. Because of continuing energy input at late times, afterglows need not uniquely reflect either the opening angle or the energy of GRBs. The structure of the jet is neither a top hat nor a (single) Gaussian, and energy and Lorentz factor do not have the same angular dependence. We speculate on the existence of other forms of high energy transients at high redshift.
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