Léo Edmond Marion,  (March 22, 1899 &ndash; July 16, 1979) was a Canadian organic chemist and academic administrator.
He was Vice-President of the National Research Council of Canada. From 1964 until 1965 he was President of the Royal Society of Canada. From 1965 until 1969, he was Dean of Faculty of Pure and Applied Science at the University of Ottawa.