Greg Stein (born March 16, 1967, in Portland, Oregon), living in Austin, Texas, United States, is a programmer, speaker, sometime standards architect, and open-source software advocate, appearing frequently at conferences and in interviews on the topic of open-source software development and use.

He was a director of the Apache Software Foundation, and served as chairman from 21 August 2002 to 20 June 2007.^[1] He is also a member of the Python Software Foundation, was a director there from 2001 to 2002,^[2] and a maintainer of the Python programming language and libraries (active from 1999 to 2002).^[3]

Stein has been especially active in version control systems development. In the late 1990s and early 2000s, he helped develop the WebDAV HTTP versioning specification,^[4] and is the main author of mod_dav, the first open-source implementation of WebDAV. He was one of the founding developers of the Subversion project,^[5] and is primarily responsible for Subversion's WebDav networking layer.

Stein most recently worked as an engineering manager at Google, where he helped launch Google's open-source hosting platform. Stein publicly announced his departure from Google via his blog on July 29, 2008.^[6] Prior to Google, he worked for Oracle Corporation, eShop, Microsoft, CollabNet, and as an independent developer.

Stein was a major contributor to the Lima Mudlib, a MUD server software framework. His MUD community pseudonym was "Deathblade".