According to legend, he is the son of Geoffrey, king of Denmark.
His son was slain by Charlot, son of Charlemagne. Seeking revenge, Ogier sought out and slew Charlot, and was only barely prevented from killing Charlemagne.
He resisted Charlemagne for seven years but made peace with him to fight at Charlemagne’s side against the Saracens, in which battle he slew the giant Brehus.
In Danish legend Ogier became a King in the Mountain; he is said to dwell in the castle of Kronborg. He will sleep there until some day when the country of Denmark is in peril, at which time he will rise up and save the nation.
In some legends, Morgue le Faye (commonly known as Morgan le Fay) took him to Avalon, from where he returned after two hundred years to save France.