Maria Theresa of Austria-Este (1849–1919)
Maria Theresa of Austria-Este (Maria Theresa Henriette Dorothee; 2 July 1849 – 3 February 1919) was the last Queen of Bavaria.
She was the daughter and only child of Archduke Ferdinand of Austria-Este and his wife, Archduchess Elisabeth of Austria.
Archduke Franz Karl of Austria
Archduke Franz Karl Joseph of Austria (17 December 1802 – 8 March 1878) was a member of the House of Habsburg-Lorraine.
He was the father of two emperors:
Franz Joseph I of Austria and Maximilian I of Mexico.
Through his third son Karl Ludwig, he was the grandfather of Archduke Franz Ferdinand of Austria – whose assassination sparked the hostilities that led to the outbreak of World War I – and the great-grandfather of the last Habsburg emperor Karl I.
Archduke Ludwig Viktor of Austria
Archduke Ludwig Viktor Joseph Anton of Austria (15 May 1842 – 18 January 1919) from the House of Habsburg was the youngest son born to Archduke Franz Karl of Austria and Princess Sophie of Bavaria and younger brother of Emperor Franz Joseph I of Austria.
Archduchess Yolande of Austria
Archduchess Yolande of Austria( née Princesse Yolande Marie Jeanne Charlotte de Ligne; born 6 May 1923) is the widow of Archduke Carl Ludwig of Austria.
Charles, Margrave of Burgau
Charles, Margrave of Burgau, also known as" Charles of Austria",( 22 November 1560 at Křivoklát Castle in Bohemia – 30 October 1618 in Überlingen), was the son of Archduke Ferdinand II of Austria and his first morganatic marriage to Philippine Welser.
He was the brother of Andrew of Austria.
Archduke Otto of Austria (1865–1906)
Archduke Otto Franz Joseph Karl Ludwig Maria of Austria (21 April 1865 – 1 November 1906) was the second son of Archduke Karl Ludwig of Austria (younger brother of Emperor Franz Joseph I of Austria) and his second wife, Princess Maria Annunciata of Bourbon-Two Sicilies.
He was the father of Charles I of Austria, the last Emperor of Austria.
Princess Sophie of Bavaria
Princess Sophie of Bavaria (Sophie Friederike Dorothea Wilhelmine;
27 January 1805 – 28 May 1872) was born to King Maximilian I Joseph of Bavaria and his second wife Caroline of Baden.
She was the identical twin sister of Princess Maria Anna of Bavaria, Queen of Saxony as wife of Frederick Augustus II of Saxony.
Her eldest son Franz Joseph reigned as Emperor of Austria, and King of Hungary; her second son Maximilian reigned as Emperor of Mexico.
Archduke Karl Ludwig of Austria
Archduke Karl Ludwig Joseph Maria of Austria( 30 July
1833 – 19 May 1896) was the younger brother of Franz Joseph I of Austria( 1830 – 1916), the father of Archduke Franz Ferdinand of Austria( 1863 – 1914), whose assassination ignited World War I, and grandfather of the last emperor, Charles I.
Eduard von Habsburg
Eduard von Habsburg( born January 12, 1967), also known as Archduke Eduard of Austria is Hungary ’s ambassador to the Holy See and Sovereign Military Order of Malta.
He is son of Archduke Michael of Austria( Archduke Joseph Francis's youngest child) and the great- great- grandson of Emperor Franz Joseph I.
He is married to Baroness Maria Theresia von Gudenus, descendant of Archduke Johann of Austria and has six children.
Archduchess Elisabeth Franziska of Austria (1892–1930)
Archduchess Elisabeth Franziska Marie Karoline Ignatia Salvator (27 January 1892 – 29 January 1930) was the eldest daughter of Archduke Franz Salvator of Austria and Archduchess Marie Valerie of Austria.
Through her mother, she was a granddaughter of Emperor Franz Joseph I of Austria.

Question: Who is Archduke Ludwig Viktor Of Austria's maternal grandfather?
Answer: Maximilian I Joseph of Bavaria