  X-ray studies of high-redshift (z > 4) active galaxies have advanced
substantially over the past few years, largely due to results from the new
generation of X-ray observatories. As of this writing X-ray emission has been
detected from nearly 60 high-redshift active galaxies. This paper reviews the
observational results and their implications for models of the first massive
black holes, and it discusses future prospects for the field.
