William Cowan Rennie (born 27 September 1967), commonly known as Willie Rennie, is a Scottish politician who served as the Leader of the Scottish Liberal Democrats from 2011 to 2021. He has served as the Member of the Scottish Parliament (MSP) for North East Fife since 2016, and previously as a list MSP for Mid Scotland and Fife (from 2011 to 2016) and as Member of Parliament (MP) for Dunfermline and West Fife (from 2006 to 2010).