Christian Matthias Ingemar Martin Matthiessen 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.
One of his major works is Lexicogrammatical cartography (1995), a 700-page study of the grammatical systems of English from the perspective of SFL.
He has co-authored a number of books with Michael Halliday.
Since 2008 he has been a professor in the Department of English at the Hong Kong Polytechnic University.
Before this, he was Chair of the Department of Linguistics at Macquarie University in Sydney.