Twenty-five years of active pulsar research have yielded a quite unexpected harvest of physical effects. These range from pleasing corroborations of well-established physical principles in unfamiliar environments to direct verification of the general theory of relativity. Pulsars have the potential for advancing our understanding of high energy nuclear physics and relativistic plasma physics. They have also enlarged our horizons in atomic physics, quantum electrodynamics and solid state physics. As extremely compact sources of regularly pulsed, high brightness radio waves, they provide excellent probes of the interstellar medium and globular clusters. The large variety of connections between pulsars and physics is illustrated with examples taken from each of these areas.