Christian Matthias Ingemar Martin Matthiessen (born 1956) is a Swedish-born linguist and a leading figure in the systemic functional linguistics (SFL) school, having authored or co-authored more than 100 books, refereed journal articles, and papers in refereed conference proceedings, with contributions to three television programs.

[1] One of his major works is Lexicogrammatical cartography (1995), a 700-page study of the grammatical systems of English from the perspective of SFL.

His mother, Christine Matthiessen, is credited with starting his interest in language as an object of study.

Matthiessen completed his undergraduate degree at Lund University in 1980, where he studied English, Arabic, and philosophy.

It was during this time that he worked with Bill Mann and Sandra Thompson in the development of rhetorical structure theory.

[12] Halliday acknowledges Matthiessen's work in extending the description of grammar from the systemic functional perspective via his contributions to the Penman project.