Luminous high-redshift radio galaxies (HzRGs) are important laboratories for studying the formation and evolution of massive galaxies, rich clusters and supermassive black holes at z > 2. They are among the most luminous and massive known galaxies in the early Universe and likely progenitors of dominant cluster galaxies. At the highest redshifts (z > 6), these powerful radio sources also have the potential to become unique probes of the epoch of reionization (EoR) through observations of the redshifted HI absorption.

Because of its low operating frequency, high sensitivity and large-sky coverage, the Low Frequency Array (LOFAR) is ideally suited to finding these rare monsters and offers an exciting new window for probing the high-redshift Universe. In this talk I will: 1) present new theoretical predictions for the expected number counts of radio-loud AGN at high-redshift, and 2) outline on-going parallel efforts to find and characterise large numbers of radio-loud AGN in both the wide and deep tiers of the LOFAR large-sky surveys; pushing HzRG studies into the EoR and providing unprecedented samples of radio-loud AGN at z > 2.