Sir Leszek Krzysztof Borysiewicz (born 13 April 1951) is a Polish-Welsh professor, immunologist and scientific administrator.
He served as the 345th Vice-Chancellor of the University of Cambridge, his term of office (a maximum of seven years) started on 1 October 2010 and ended on 1 October 2017.
Borysiewicz also served as chief executive of the Medical Research Council of the UK from 2007-2010.