Shortly after Steven Cook and Richard Karp showed the existence of many natural NP-complete languages, researchers started to realize the great importance of the P versus NP problem and the difficulty of settling it. One graduate student at the Massachusetts Institute of Technology started to look beyond NP, asking what problems have a higher complexity and how do we classify them. Larry Stockmeyer discovered an amazing structure of complexity classes that continues to direct the research in complexity to this day. Stockmeyer passed away on July 31, 2004 at the age of 55 and in this paper we review some of his research and the legacy he has left on the community. Categories and Subject Descriptors K.2 [History of Computing]: [Theory, People];