X-rays Surveys: Past, Present and Future

The X-ray sky is filled with a variety of sources ranging from nearby common stars to exotic super-massive black holes at the centers of distant galaxies. The story of how we have come to know of these objects spans about 50 years of X-ray observations. Key to the discovery of the complex and beautiful X-ray universe are the various large surveys that have been carried out with ever increasing sensitivity and precision. I will review several of these missions, highlighting some of their major discoveries, and then summarize the more recent survey work being done with currently operating facilities. Finally, I will discuss plans for the future, in particular new missions to carry out sensitive all-sky or large area surveys surpassing by orders of magnitude those last done in the 1990's.