The LIGO and Virgo interferometers have observed almost 100 gravitational-wave signals from collisions of black holes and neutron stars. Meanwhile, pulsar timing arrays around the globe are beginning to see interesting signals that may be attributed to a gravitational-wave stochastic background, potentially from supermassive black hole binaries throughout the Universe, or even primordial gravitational waves from the very early Universe. In this talk, I will review the state of both ground-based gravitational-wave astronomy and pulsar timing arrays. I will also discuss our ability to use current and future gravitational-wave observations to test Einstein’s general theory of relativity in the ultra-strong field regime.