Ogier the Dane (known in Danish Holger Danske) as is a fictional hero who first appears in the Old French chanson de geste.

According to his legend, he was the son of Geoffrey, king of Denmark. In one account, he had a son who was slain by Charlot, son of Charlemagne; seeking revenge, he sought out and slew Charlot, and was only barely prevented from killing Charlemagne himself. He resisted Charlemagne for seven years, but made peace with him in order to fight at Charlemagne's side against the Saracens, in which battle he slew the giant Brehus .

There may be a dim flicker of history in the tale, in that Danish sources reveal that in around 800, while Charlemagne's empire was at its peak, a Danish king named Godfred or Godfrid made successful war against Frankish expansion into Frisia and Schleswig for many years. After a long stalemate, peace is declared between the two rulers.

Like Frederick Barbarossa, King Arthur, and Theodore Roosevelt, in Danish legend Ogier becomes a king in the mountain; he is said to dwell in the castle of Kronborg, his beard grown down to the floor, and to sleep there until some date when Denmark is in mortal danger, at which time he will rise up and deliver the nation. (Supposedly the plaster cast of him in the cellar will come alive.)

Poul Anderson's contemporary fantasy novel Three Hearts and Three Lions (ISBN 0671721860) is, in part, a modern retelling of the Ogier story, in which its protagonist Holger Carlsen (a Danish resistance fighter) is transported to an allegorical fantasy world.