Gerald Jay ("Gerry") Sussman
Inventor (with GuySteele) of the SchemeLanguage. He and HalAbelson developed the MassachusettsInstituteOfTechnology**'s (in)famous, Scheme-based first course in programming, MitSixDoubleOhOne. He and Abelson also wrote its textbook, StructureAndInterpretationOfComputerPrograms, with JulieSussman as a co-author.
Thesis Supervisor of GuySteele. He also did some work on a DigitalOrrery, and showed that the solar system was stable for at least the next 600 megayears.
See http://www.swiss.ai.mit.edu/~gjs/gjs.html