Stephen J. Mellor (born 1952) is an American computer scientist, developer of the Ward–Mellor method for real-time computing, the Shlaer–Mellor method, and Executable UML, and signatory to the Agile Manifesto.
Mellor received a BA in computer science from the University of Essex in 1974, and started working at CERN in Geneva, Switzerland as a programmer in BCPL.
In 1977 he became software engineer at the Lawrence Berkeley Laboratory, and in 1982 consultant at Yourdon, Inc.[1] At Yourdon in cooperation with Paul Ward they developed the Ward–Mellor method, and published the book-series Structured Development for Real Time Systems in 1985.
[1] Mellor stayed as chief scientist of the Embedded Systems Division at Mentor Graphics for another two years, and is self-employed since 2006.
Since 1998 Mellor has contributed to the Object Management Group, chairing the consortium that added executable actions to the UML, and the specification of model-driven architecture (MDA).