The Fermi Gamma-ray Space Telescope, sensitive from 20 MeV to over 300 GeV, has made new measurements covering a broad range of topics in astrophysics and particle physics during its first two years of operation. HESS, MAGIC, and VERITAS are continuing to make new discoveries in the 100 GeV to 30 TeV range. The simultaneous operation of these instruments, along with the upcoming operation of CTA and HAWC, constitute a golden age for gamma-ray astronomy. Fermi detected 1451 GeV sources in its first year of operation, and the TeV telescopes have increased the number of known TeV sources by an order of magnitude in the past few years. In addition to enabling new discoveries about the high-energy universe, these instruments are providing measurements of fundamental physics. They have placed stringent constraints on Lorentz invariance violation and made the best measurements of the cosmic ray electron + positron spectrum in the 7 GeV to 4 TeV range. Together with neutrino telescopes, gamma-ray telescopes could elucidate both the mechanisms of cosmic ray acceleration and the nature of dark matter in the next decade.