 Discoveries include an isotropic distribution of gamma-ray bursts (GRBs) on the sky, supporting an extragalactic origin, two classes of GRBs with short and long durations, blazars with bright gamma-ray emission and harder spectra than Seyfert AGN (e.g., Dermer & Gehrels 1995), detailed mapping of gamma-rays from Al-26 decay in the galactic plane mapping regions of nucleosynthesis over the past million years, and detailed mapping of the 511 keV line from positron annihilation in the galaxy with concentration at the galactic center.Gehrels et al.