High-energy and multimessenger astrophysics are frontiers for discovery that uniquely provide access to the extreme processes that sculpt the universe. As a priority theme of the Astro2020 Decadal Survey report: New Messengers New Physics, this science is poised to revolutionize our understanding of the extreme universe. Data from NASA’s Fermi and Swift missions demonstrated that the extreme processes that produce gravitational waves and accelerate neutrinos and cosmic rays also produce the highest energy for of light: gamma rays. This talk presents the exciting discoveries in high-energy and multimessenger astrophysics over the past several years and looks forward to how we can fully capitalize on this exciting new era in the future.