Namesakes
Austrian Dukes and Emperors:
1 emperor
Emperor Karl I (middle name Ludwig) 1916-1918 
Bohemian Kings:
1 king
King Karel III (middle name Ludwig) 1916-1918
German Chancellors and Presidents:
1 chancellor
(chancellor) Ludwig Erhard 1963-1966
German Kings and Holy Roman Emperors:
2 emperors, 1 king, 1 king-emperor
Emperor Ludwig I the Pious 813-840
Emperor Ludwig II the Younger 844-875
King Ludwig III the Child 900-911
King-Emperor Ludwig IV 1314-1347
Greek Prime Ministers:
1 prime minister
Josef Ludwig von Armansperg 1835-1837
Hungarian Kings and Queens:
1 king
King Károly IV (middle name Ludwig) 1916-1918
Nobel Prize Winners:
2 physics, 1 peace
(physics) Gustav Ludwig Hertz 1925
(peace) Ludwig Quidde 1927
(physics) Horst Ludwig Störmer 1998
Norwegian Prime Ministers:
1 prime minister
Johan Ludwig Mowinckel 1924-1926; 1928-1931; 1933-1935
Notable Actors and Entertainers:
1 entertainer/magician
Roy Horn (middle name Ludwig) 1944-2020
Notable Artists:
1 architect, 1 painter
Ernst Ludwig Kirchner 1880-1938
Ludwig Mies van der Rohe 1886-1969
Notable Athletes:
1 soccer
(soccer) Ludwig Augustinsson 1994-
Notable Musicians:
1 composer, 1 singer
Ludwig van Beethoven 1770-1827
Rex Gildo (a.k.a. Ludwig) 1936-1999
Notable Philosophers and Thinkers:
2 philosophers, 1 linguist
Ljudevit Gaj (a.k.a. Ludwig) 1809-1872
Ludwig von Strümpell 1812-1899
Ludwig Wittgenstein 1889-1951
Notable Politicians and Statespeople:
1 politician
Adolf Grimme (middle name Ludwig) 1889-1963
Notable Scientists and Inventors:
4 physicists, 1 chemist
Adolph Strecker (middle name Ludwig) 1822-1871
Ludwig Boltzmann 1844-1906
Gustav Mie (middle name Ludwig) 1868-1957
Gustav Ludwig Hertz 1887-1975
Horst Ludwig Störmer 1949-
Olympic Medalists:
2 bronze, 1 silver
(bronze) Ludwig Wrede 1928 figure skating
(silver) Luz Long (middle name Ludwig) 1936 long jump
(bronze) Heinz Fütterer (middle name Ludwig) 1956 4x100 m relay
Other Royalty:
8 princes, 6 archdukes, 1 king, 1 king/emperor
Heinrich of Prussia (middle name Ludwig) 1726-1802 Prussia
Louis Ferdinand of Prussia (middle name Ludwig) 1772-1806 Prussia
Ludwig of Prussia 1773-1796 Prussia
Friedrich of Prussia (middle name Ludwig) 1794-1863 Prussia
Alexander of Prussia (middle name Ludwig) 1820-1896 Prussia
Karl Ludwig of Austria 1833-1896 Austria-Hungary
Ludwig Viktor of Austria 1842-1919 Austria-Hungary
Franz Ferdinand of Austria (middle name Ludwig) 1863-1914 Austria-Hungary
Ludwig II of Bavaria 1864-1886 Bavaria
Otto Franz Joseph of Austria (middle name Ludwig) 1865-1906 Austria-Hungary
Ferdinand Karl of Austria (middle name Ludwig) 1868-1911 Austria-Hungary
Wilhelm I (middle name Ludwig) 1861-1888; 1871-1888 Prussia; German Empire
Waldemar of Prussia (middle name Ludwig) 1889-1945 Prussia
Maximilian Eugen of Austria (middle name Ludwig) 1895-1919 Austria-Hungary
Heinrich of Prussia (middle name Ludwig) 1900-1904 Prussia
Karl Ludwig of Liechtenstein 2016- Liechtenstein
Saints:
2 blessed
Blessed Louis of Thuringia (a.k.a. Ludwig) 1200-1227
Blessed Karl of Austria (middle name Ludwig) 1887-1922
Swiss Presidents:
2 presidents
Ludwig Forrer 1906; 1912
Ludwig von Moos 1964; 1969