Ernest II (German: Ernst August Karl Johann Leopold Alexander Eduard; 21 June 1818 – 22 August 1893) was the sovereign duke of the Duchy of Saxe-Coburg and Gotha, reigning from 1844 to his death. Ernest was born in Coburg as the eldest child of Ernest I, Duke of Saxe-Coburg-Saalfeld, and his duchess, Princess Louise of Saxe-Gotha-Altenburg. Fourteen months later, his younger brother Prince Albert was born, who became consort of Queen Victoria of the United Kingdom. Ernest's father became Duke of Saxe-Coburg and Gotha in 1826 through an exchange of territories.
In 1842, Ernest married Princess Alexandrine of Baden in what was to be a childless marriage. Soon after, he succeeded as duke upon the death of his father on 29 January 1844. As reigning Duke Ernest II, he supported the German Confederation in the Schleswig-Holstein Wars against Denmark, sending thousands of troops and becoming the commander of a German corps; as such, he was instrumental in the 1849 victory at the battle of Eckernförde against Danish forces. After King Otto of Greece was deposed in 1862, the British government put Ernest's name forward as a possible successor. Negotiations fell through however for various reasons, not in the least of which was that he would not give up his beloved duchies in favor of the Greek throne.
A supporter of a unified Germany, Ernest watched the various political movements with great interest. While he initially was a great and outspoken proponent of the liberal movement, he surprised many by switching sides and supporting the more conservative (and eventually victorious) Prussians during the Austro-Prussian and Franco-Prussian wars and subsequent unification of Germany. His support of the conservatives came at a price however, and he was no longer viewed as the possible leader of a political movement. According to historian Charlotte Zeepvat, Ernest became "increasingly lost in a whirl of private amusements which earned only contempt from outside".
Ernest's position was often linked to his brother Prince Albert, husband of Queen Victoria. The two boys were raised as though twins, and became closer upon the separation and divorce of their parents, as well as the eventual death of their mother. The princes' relationship experienced phases of closeness as well as minor arguments as they grew older; after Albert's death in 1861, Ernest became gradually more antagonistic to Victoria and her children, as well as increasingly bitter toward the United Kingdom, publishing anonymous pamphlets against various members of the British royal family. Despite their increasingly differing political views and opinions however, Ernest accepted his second eldest nephew Prince Alfred, Duke of Edinburgh as his heir-presumptive, who upon Ernest's death on 22 August 1893 at Reinhardsbrunn, succeeded to the ducal throne.