Ernst I, Duke of Saxe-Altenburg
Ernst I, Duke of Saxe- Altenburg( German: Ernst I. Friedrich Paul Georg Nikolaus von Sachsen- Altenburg)( 16 September 1826 in Hildburghausen – 7 February 1908 in Altenburg), was a duke of Saxe- Altenburg.
He was the first son of Georg, Duke of Saxe- Altenburg and Marie Luise of Mecklenburg- Schwerin.
In 1853 he succeeded his father as Duke of Saxe- Altenburg.
He was of a retiring disposition and he took little active part in running the country.
After a reign that lasted fifty five years, he died without a living direct male heir; because of this, he was succeeded by his nephew, Ernst.
Princess Elisabeth Sophie of Saxe-Altenburg
Elisabeth Sophie of Saxe- Altenburg( 10 October 1619 – 20 December 1680), was a princess of Saxe- Altenburg and, by marriage, duchess of Saxe- Gotha.
She was born in Halle, the only daughter of Johann Philipp, Duke of Saxe- Altenburg, and his wife, Elisabeth of Brunswick- Wolfenbüttel.
Prince Eduard of Saxe-Altenburg
Eduard Karl Wilhelm Christian of Saxe- Altenburg( Hildburghausen, 3 July 1804 – Munich, 16 May 1852), was a German prince of the ducal house of Saxe- Hildburghausen( of Saxe- Altenburg from 1826).
Prince Moritz of Saxe-Altenburg
Prince Moritz Franz Friedrich Constantin Alexander Heinrich August Carl Albrecht of Saxe- Altenburg( 24 October 1829 in Eisenberg – 13 May 1907 in Arco, Italy), was a member of the ducal house of Saxe- Altenburg.
He was the father of Ernst II, Duke of Saxe- Altenburg.
Princess Antoinette of Saxe-Altenburg
Princess Antoinette of Saxe- Altenburg( 17 April 1838 – 13 October 1908) was a princess of Saxe- Altenburg by birth and Duchess of Anhalt by marriage.
Princess Elisabeth of Saxe-Altenburg (1826–1896)
Princess Elisabeth Pauline Alexandrine of Saxe-Altenburg (26 March 1826 – 2 February 1896) was a daughter of Joseph, Duke of Saxe-Altenburg and his wife Duchess Amelia of Württemberg.
By marriage, she became Grand Duchess of Oldenburg.
Duchess Amelia of Württemberg
Amalie Therese Louise Wilhelmina Philippine of Württemberg (28 June 1799 – 28 November 1848) was a Duchess of Württemberg and an ancestor of Greek, Romanian, Yugoslavian and Spanish Royal Families.
She was a daughter of Duke Louis of Württemberg and Princess Henrietta of Nassau-Weilburg.
Georg Moritz, Hereditary Prince of Saxe-Altenburg
George Moritz, Hereditary Prince of Saxe- Altenburg(" William George Moritz Ernest Albert Frederick Charles Constantine Edward Maximilian"; 13 May 1900 – 13 February 1991), was the last head of the ducal house of Saxe- Altenburg and nominal Duke of Saxe- Altenburg.
He devoted much of his life to promote anthroposophy.
Princess Marie Anne of Saxe-Altenburg
Princess Marie Anne of Saxe- Altenburg( 14 March 1864 – 3 May 1918) was the consort of Georg, Prince of Schaumburg- Lippe.
As the eldest daughter of Prince Moritz of Saxe- Altenburg and his wife Princess Augusta of Saxe- Meiningen, and a sister of Ernest II, Duke of Saxe- Altenburg, Marie Anne was a member of the Ducal House of Saxe- Altenburg.
Princess Charlotte of Saxe-Altenburg
Princess Charlotte Agnes of Saxe- Altenburg( 4 March 189916 February 1989) was the eldest child of Ernst II, the last reigning duke of Saxe- Altenburg.

Question: Who is the maternal grandfather of Princess Elisabeth Of Saxe-Altenburg (1826–1896)?
Answer: Duke Louis of Württemberg