Ernest I, Duke of Saxe-Coburg and Gotha

Ernest I, Duke of Saxe-Coburg and Gotha (Ernst Anton Karl Ludwig Herzog von Sachsen-Coburg und Gotha; 2 January 1784 – 29 January 1844), was as Ernest III the last sovereign duke of Saxe-Coburg-Saalfeld, and from 1826, the first sovereign duke of Saxe-Coburg and Gotha.

He was the eldest son of Francis, Duke of Saxe-Coburg-Saalfeld, and Countess Augusta of Reuss-Ebersdorf. His younger brother, Leopold Georg Christian Frederick, was later elected the first King of the Belgians.

On 10 May 1803 he was hurriedly proclaimed an adult, because his father became gravely ill in the spring of that year, and he was required to take part in the government of the duchy. When his father died in 1806, he succeeded in the duchy of Saxe-Coburg-Saalfeld as "Ernest III", but could not take over the formal government of his lands, because the duchy was occupied by Napoleonic troops and was under French administration. Only after the Peace of Tilsit (1807) was the duchy of Saxe-Coburg-Saalfeld reunited (first having been dissolved) and returned to Ernest. This occurred through Russian pressure, since his sister Juliane was married to the brother of the Russian Tsar.

Ernest was a Prussian general and participated in military actions against Napoleon. He fought in the battles of Auerstedt (1806), Lützen and Leipzig (1813) and drew in 1814 into the French fortress of Mainz. After the defeat of Napoleon in the Battle of Waterloo, the Congress of Vienna on 9 June 1815 gave him an area of 8.25 sqmi with 25,000 inhabitants around the capital St. Wendel. In 1819 this land received the name of Principality of Lichtenberg. He sold it to Prussia in 1834.

In Gotha on 3 July 1817 Ernest married Princess Louise of Saxe-Gotha-Altenburg. They had two children:
 * 1) Ernest II Augustus Charles John Leopold Alexander Edward, Duke of Saxe-Coburg-Gotha
 * 2) Francis Augustus Charles Albert Emmanuel, better known as "Albert", the husband of Queen Victoria and Prince Consort of the United Kingdom.

His marriage was unhappy due to his own acts of infidelity. Ernest and Louise were separated in 1824 and were officially divorced on 31 March 1826. Despite being the innocent party, Louise was parted from her children and died at 30.

The death in 1825 of the last duke of Saxe-Gotha-Altenburg, Louise's uncle, resulted in a rearrangement of the Ernestine duchies. Ernest at the time was in the process of divorcing Louise, and because of this the other branches objected to him receiving Gotha. They reached a compromise on 12 November 1826: Ernest received Gotha and ceded Saalfeld to Saxe-Meiningen. He subsequently became "Ernest I, Duke of Saxe-Coburg and Gotha".

In Coburg on 23 December 1832, Ernest married for a second time to his niece Duchess Marie of Württemberg, the daughter of his sister Antoinette. They had no children. This marriage made Marie both Prince Albert's cousin and his stepmother.

Ernest had three illegitimate children:

—With Sophie Fermepin de Marteaux:
 * 1) Berta Ernestine von Schauenstein (b. 26 January 1817 – d. Coburg, 15 August 1896), married her first cousin Eduard Edgar Schmidt-Löwe von Löwenfels, the illegitimate son of her father's sister, Juliane.

—With Margaretha Braun:
 * 1) Ernst Albert Bruno von Bruneck (d. 1838).
 * 2) Robert Ferdinand von Bruneck (d. 1856), created in 1856 Freiherr von Bruneck.

He is the patrilineal ancestor of, inter alios, both the Duke of Gloucester and Duke of Kent, as well as being the great-great-great-grandfather of Queen Elizabeth II.