| Ernst Gunther | |
| Duke of Schleswig-Holstein | |
| House: | Schleswig-Holstein-Sonderburg-Augustenburg |
| Father: | Frederick VIII, Duke of Schleswig-Holstein |
| Mother: | Princess Adelheid of Hohenlohe-Langenburg |
| Spouse: | Princess Dorothea of Saxe-Coburg and Gotha |
| Birth Date: | 11 August 1863 |
| Birth Place: | Dolzig, Brandenburg, Prussia |
| Death Place: | Primkenau, Lower Silesia, Prussia, Germany |
| Religion: | Lutheran |
Ernst Gunther II, Duke of Schleswig-Holstein (11 August 1863 - 22 February 1921), was a son of Frederick VIII, Duke of Schleswig-Holstein and Princess Adelheid of Hohenlohe-Langenburg. He inherited his father's title as titular third duke of Schleswig-Holstein.
On 2 August 1898 in Coburg, Saxe-Coburg and Gotha, he married Princess Dorothea of Saxe-Coburg and Gotha, daughter of Prince Philipp of Saxe-Coburg and Gotha and Princess Louise of Belgium. The grandfather of the bride, King Leopold II, did not attend the wedding but sent the Grand Cordon of the Order of Leopold as wedding gift.
The couple had no children. However, on 11 November 1920, Ernst Gunther adopted Prince Johann Georg (24 July 1911 – killed in Russia 23 June 1941) and his sister Princess Marie Luise (1908–1969, married 1st 1934 and div 1955 Rudolf Karl Freiherr von Stengel and married 2nd 1962 Friedrich Christian Prince zu Schaumburg-Lippe), children of his cousin Prince Albrecht of Schleswig-Holstein-Sonderburg-Glücksburg (1863–1948).[1]
He received the following orders and decorations:[2]