Tobias Simpson Menzies (born March 7, 1974) is a British stage, television, and film actor, best known for his roles as Frank Randall / Jonathan \'Black Jack\' Randall on Outlander, Edmure Tully on HBO\'s Game of Thrones, Prince Philip - Duke of Edinburgh on The Crown, Geoffrey Dromgoole on The Night Manager, Nathaniel Bloom on The Honourable Woman, and as Marcus Junius Brutus in HBO\'s series Rome.