Mary Louise McDonald (born 1 May 1969) is an Irish Sinn Féin politician. In June 2020, she became Leader of the Opposition. She is the Leader of Sinn Féin since February 2018 and Teachta Dála (TD) for Dublin Central since the 2011 general election. She was Deputy Leader of Sinn Féin from 2009 to 2018 and Member of the European Parliament (MEP) for Dublin from 2004 to 2009.