Matthew Hennessy is an Irish computer scientist who has contributed especially to concurrency (computer science), process calculi and programming language semantics.
Hennessy was Professor of Computer Science at the Department of Informatics, University of Sussex, England, until 2008. Since then, Hennessy has held a professorship at the Department of Computer Science, Trinity College, Dublin.
Hennessy's research interests are in the area of the semantic foundations of programming and specification languages, particularly involving distributed computing, including mobile computing. He also has an interest in verification tools.