Roger Lass (born January 1, 1937) is a historical linguist, currently an honorary professorial fellow at the University of Edinburgh.
He earned his PhD from Yale University in 1965 in Medieval English Language and Literature, and subsequently worked at Indiana University (1964–1971), the University of Edinburgh (1972–1982), and the University of Cape Town (1983–2002).
He has done extensive work in the history of English, the motivation of sound change, and the history of linguistics. He was made an honorary professorial fellow at Edinburgh in 2014.
He was the editor of the third volume of The Cambridge History of the English Language.