Raspbian primarily the result of two developers: Mike Thompson and Peter Green.
Mike Thompson (aka mpthompson in the forums and IRC) is a Computer Engineer with a diverse background in embedded systems design, handheld/mobile application development, PC application development and large scale Internet systems design. He's also a serial entrepreneur who co-founded multiple start-up companies in Silicon Valley. Currently, Mike enjoys being a full-time father with the freedom and flexibility to take on "labor of love" projects such as Raspbian while waiting for the opportunity to begin his next entrepreneurial venture. Mike can be contacted at mpthompson(at)raspbian(dot)org.
Peter Green (aka plugwash in the forums and IRC) is a PHD student studying electrical engineering (specifically wireless sensor networks) at the University of Manchester. He has been a debian user for some time and recently got involved in the arm porting and became a debian developer.