Strong-randomness renormalization groups

This is a very brief review article, written for a book (in preparation) in memory of Michael E. Fisher and to celebrate 50+ years since the Wilson-Fisher renormalization group. Strong-randomness renormalization groups were first developed to treat various quantum critical ground states, especially in one-dimensional systems. After briefly reviewing some of the earlier work with these methods, the recent application of this approach to the many-body localization (MBL) phase transition is reviewed.