Michelle O'Neill named the new leader of Sinn Féin in the North. Watch an exclusive interview [email protected] grandcasinoonline.net. Sinn Féin has announced that Michelle O'Neill is to replace Martin McGuinness as its leader north of the border. She had been widely tipped as. The leader of Sinn Féin is the most senior politician within the Sinn Féin political party in Ireland. Since 13 November , the office has been held by Gerry Background · Presidents · Vice Presidents · Parliamentary party leaders.