Albert, Duke of Schleswig-Holstein (Albert John Charles Frederick Alfred George; 26 February 1869 – 27 April 1931), was a grandson of Queen Victoria. He was the second son of Victoria's daughter, Princess Helena, by her husband Prince Christian of Schleswig-Holstein. He was the head of the House of Oldenburg and also the House of Schleswig-Holstein-Sonderburg-Augustenburg and the Duke of Schleswig-Holstein between 1921 and 1931.

Prince Albert grew up at Cumberland Lodge in Windsor Great Park. Like his elder brother, Prince Christian Victor, whom he followed to Lambrook Preparatory School in Berkshire, Albert was destined for a military career. However, while Christian Victor's was in the British Army, Albert served with the Prussian Army, reaching the rank of Lieutenant Colonel in the 3rd Uhlans of the Guard. During World War I he was excused from service against the British by the German Emperor, and spent the war in Berlin on the staff of the Governor of the city.

In 1921, the Prince succeeded as the head of the Schleswig-Holstein-Sonderburg-Augustenburg of the House of Schleswig-Holstein, following his childless cousin Duke Ernst Gunther of Schleswig-Holstein-Sonderburg-Augustenburg. This was the senior branch of the House of Oldenburg, to which the Duke of Schleswig-Holstein-Sonderburg-Glücksburg, the King of Denmark, the King of Norway, the King of the Hellenes, the former Grand Duke of Oldenburg and the Russian Imperial Family belonged.