Namesakes
Austrian Chancellors and Presidents:
1 chancellor
(chancellor) Otto Ender 1930-1931 
Austrian Dukes and Emperors:
1 duke, 1 emperor
Duke Otto the Merry 1330-1339
Emperor Karl I (middle name Otto) 1916-1918
Bohemian Kings:
1 king
King Karel III (middle name Otto) 1916-1918
Danish Prime Ministers:
3 prime ministers
Tage Reedtz-Thott (middle name Otto) 1894-1897
Otto Liebe 1920
Jens Otto Krag 1962-1968; 1971-1972
Estonian Presidents and Prime Ministers:
1 prime minister, 1 prime minister/state elder
(prime minister/state elder) Otto Strandman 1919; 1929-1931
(prime minister) Otto Tief 1944
Fictional Characters from Television:
1 character
Otto Flick 1982 'Allo 'Allo!
German Chancellors and Presidents:
1 chancellor
(chancellor) Otto von Bismarck 1871-1890
German Kings and Holy Roman Emperors:
4 king-emperors
King-Emperor Otto I the Great 936-973
King-Emperor Otto II the Red 961-983
King-Emperor Otto III 983-1002
King-Emperor Otto IV 1198-1215
Hall-of-Famers:
1 football
(football) Otto Graham 1965
Hungarian Kings and Queens:
2 kings
King Ottó III of Bavaria 1305-1308
King Károly IV (middle name Otto) 1916-1918
Hungarian Presidents and Prime Ministers:
1 prime minister
Prime Minister Dénes Berinkey (middle name Ottó) 1919
Hurricanes and Tropical Storms:
2 hurricanes, 1 storm
Storm Otto 2004
Hurricane Otto 2010
Hurricane Otto 2016
Nobel Prize Winners:
6 chemistry, 3 medicine, 1 physics
(chemistry) Otto Wallach 1910
(medicine) Otto Fritz Meyerhof 1922
(chemistry) Heinrich Otto Wieland 1927
(chemistry) Adolf Windaus (middle name Otto) 1928
(medicine) Otto Heinrich Warburg 1931
(medicine) Otto Loewi 1936
(physics) Otto Stern 1943
(chemistry) Otto Hahn 1944
(chemistry) Otto Diels 1950
(chemistry) Ernst Otto Fischer 1973
Norwegian Prime Ministers:
2 prime ministers
Otto Blehr 1921-1923
Otto B. Halvorsen 1920-1921; 1923
Notable Artists:
4 painters, 1 architect, 1 fashion designer
Otto Wagner 1841-1918
Georg von Rosen (middle name Otto) 1843-1923
Otto Hesselbom 1848-1913
Otto Mueller 1874-1930
Otto Dix 1891-1969
Karl Lagerfeld (middle name Otto) 1933-2019
Notable Athletes:
1 football, 1 soccer
(football) Otto Graham 1921-2003
(soccer) Otto Rehhagel 1938-
Notable Evildoers:
1 persecutor
Adolf Eichmann (a.k.a. Otto) 1906-1962
Notable Filmmakers:
1 director
Otto Preminger 1905-1986
Notable Scientists and Inventors:
4 chemists, 2 physicists, 1 naturalist
Otto von Guericke 1602-1686
Otto Friedrich Müller 1730-1784
Otto Wallach 1847-1931
Otto Diels 1876-1954
Adolf Windaus (middle name Otto) 1876-1959
Otto Hahn 1879-1968
Otto Stern 1888-1969
Olympic Medalists:
4 bronze, 4 silver, 2 gold, 1 bronze/gold, 1 gold/silver, 1 silver/bronze
(silver) Otto Herschmann 1896 swimming - 100 m freestyle
(silver/bronze) Otto Wahle 1900; 1904 swimming - 1500 m freestyle; swimming - 200 m obstacle; swimming - 400 m freestyle
(bronze) Otto Nilsson 1908 javelin throw
(silver) Otto Trieloff 1908 medley relay
(bronze) Otto Scheff 1908 swimming - 400 m freestyle
(gold) Eric Lemming (middle name Otto) 1908; 1912 javelin throw - freestyle; javelin throw
(silver) Otto Fahr 1912 swimming - 100 m backstroke
(silver) Otto Neumann 1928 4x400 m relay
(gold/silver) Otto Cordes 1928; 1932 water polo
(gold) Hans Woellke (middle name Otto) 1936 shot put
(bronze) Ruud van Feggelen (middle name Otto) 1948 water polo
(bronze) Herbert Schade (middle name Otto) 1952 5000 m
(bronze/gold) Ottó Boros 1956; 1960; 1964 water polo
Other Royalty:
1 king, 1 prince consort
Otto of Greece 1832-1862 Greece
Claus of the Netherlands (middle name Otto) 1980-2002 Netherlands
Saints:
2 blessed, 1 saint
Saint Otto of Bamberg 1060-1139
Blessed Otto Neururer 1882-1940
Blessed Karl of Austria (middle name Otto) 1887-1922
Swiss Presidents:
1 president
Otto Stich 1988; 1994
Tolkien's Characters:
1 character
Otto Boffin (m)