Christopher Alexander is one of those guys that gets called "seminal" and not for reasons resembling Bill Clinton's. No, in Alexander's case, it's because his books, especially A Pattern Language and The Timeless Way of Building, started all kinds of movements. In software, design patterns started in object-oriented design and programming culture (mostly Smalltalk and C++) and spread outward from there. In architecture, though Alexander's intended idea of enabling every person to design and build his own home was not borne out, these books and his others still had a strong effect.

Alexander has his own website at patternlanguage.com. His newest hit book is The Nature of Order, which talks about centers instead of patterns.