Paul Leach is a Distinguished Engineer working as an architect in the Windows Security group. Since joining Microsoft, he has worked on the Distributed COM and Interactive TV programs.

Leach was a founder of Apollo Computer and an Apollo Fellow, where he was the chief architect of the Apollo Domain and the Network Computing System, which became a major part of the OSF DCE.

Leach also holds an appointment as auxiliary professor in the Department of Computer Science and Engineering at the University of Washington. He is a co-author of the HTTP/1.1 protocol specification and several security related IETF RFCs, and holds 29 US patents.