Namesakes
Adolf Eichmann
(a.k.a. Otto) (m) 1906-1962 
Notable Evildoers
Adolf Windaus
(middle name Otto) (m) 1876-1959
Nobel Prize Winners 1928 (chemistry)
Notable Scientists and Inventors
Claus of the Netherlands
(middle name Otto) (m) 1926-2002
Other Royalty 1980-2002 Netherlands (prince consort)
Dénes Berinkey
(middle name Ottó) (m) 1871-1944
Hungarian Presidents and Prime Ministers 1919 (prime minister)
Eric Lemming
(middle name Otto) (m) 1880-1930
Olympic Medalists 1908; 1912 javelin throw - freestyle; javelin throw (gold)
Ernst Otto Fischer
(m) 1918-2007
Nobel Prize Winners 1973 (chemistry)
Georg von Rosen
(middle name Otto) (m) 1843-1923
Notable Artists
Hans Woellke
(middle name Otto) (m) 1911-1943
Olympic Medalists 1936 shot put (gold)
Heinrich Otto Wieland
(m) 1877-1957
Nobel Prize Winners 1927 (chemistry)
Herbert Schade
(middle name Otto) (m) 1922-1994
Olympic Medalists 1952 5000 m (bronze)
Jens Otto Krag
(m) 1914-1978
Danish Prime Ministers 1962-1968; 1971-1972
Jonathan Motzfeldt
(middle name Otto) (m) 1938-2010
Other Leaders 1979-1991; 1997-2002 Greenland (prime minister)
Karel III
(middle name Otto) (m) 1887-1922
Bohemian Kings 1916-1918
Austrian Dukes and Emperors (Karl I) 1916-1918
Saints (Karl of Austria)
Karl Lagerfeld
(middle name Otto) (m) 1933-2019
Notable Artists
Károly IV
(middle name Otto) (m) 1887-1922
Hungarian Kings and Queens 1916-1918
Otto I the Great
(m) 912-973
German Kings and Holy Roman Emperors 936-973
Otto II the Red
(m) 955-983
German Kings and Holy Roman Emperors 961-983
Otto III
(m) 980-1002
German Kings and Holy Roman Emperors 983-1002
Otto of Bamberg
(m) 1060-1139
Saints
Otto IV
(m) 1175-1218
German Kings and Holy Roman Emperors 1198-1215
Ottó III of Bavaria
(m) 1261-1312
Hungarian Kings and Queens 1305-1308
Otto the Merry
(m) 1301-1339
Austrian Dukes and Emperors 1330-1339
Otto of Greece
(m) 1815-1867
Other Royalty 1832-1862 Greece (king)
Otto Franz Joseph of Austria
(m) 1865-1906
Other Royalty 1865-1906 Austria-Hungary (archduke)
Otto
(m)
Hurricanes and Tropical Storms 2004 (storm)
Otto
(m)
Hurricanes and Tropical Storms 2010 (hurricane)
Otto
(m)
Hurricanes and Tropical Storms 2016 (hurricane)
Otto Blehr
(m) 1847-1927
Norwegian Prime Ministers 1921-1923
Otto Boffin
(m)
Tolkien's Characters
Ottó Boros
(m) 1929-1988
Olympic Medalists 1956; 1960; 1964 water polo (bronze/gold)
Otto Cordes
(m) 1905-1970
Olympic Medalists 1928; 1932 water polo (gold/silver)
Otto Diels
(m) 1876-1954
Nobel Prize Winners 1950 (chemistry)
Notable Scientists and Inventors
Otto Dix
(m) 1891-1969
Notable Artists
Otto Ender
(m) 1875-1960
Austrian Chancellors and Presidents 1930-1931 (chancellor)
Otto Fahr
(m) 1892-1969
Olympic Medalists 1912 swimming - 100 m backstroke (silver)
Otto Flick
(m)
Fictional Characters from Television 1982 'Allo 'Allo!
Otto Graham
(m) 1921-2003
Hall-of-Famers 1965 (football)
Notable Athletes (football)
Otto Hahn
(m) 1879-1968
Nobel Prize Winners 1944 (chemistry)
Notable Scientists and Inventors
Otto B. Halvorsen
(m) 1872-1923
Norwegian Prime Ministers 1920-1921; 1923
Otto Herschmann
(m) 1877-1942
Olympic Medalists 1896 swimming - 100 m freestyle (silver)
Otto Hesselbom
(m) 1848-1913
Notable Artists
Otto Liebe
(m) 1860-1929
Danish Prime Ministers 1920
Otto Loewi
(m) 1873-1961
Nobel Prize Winners 1936 (medicine)
Otto Fritz Meyerhof
(m) 1884-1951
Nobel Prize Winners 1922 (medicine)
Otto Mueller
(m) 1874-1930
Notable Artists
Otto Friedrich Müller
(m) 1730-1784
Notable Scientists and Inventors
Otto Neumann
(m) 1902-1990
Olympic Medalists 1928 4x400 m relay (silver)
Otto Neururer
(m) 1882-1940
Saints
Otto Nilsson
(m) 1879-1960
Olympic Medalists 1908 javelin throw (bronze)
Otto Preminger
(m) 1905-1986
Notable Filmmakers
Otto Rehhagel
(m) 1938-
Notable Athletes (soccer)
Otto Sander
(m) 1941-2013
Notable Actors and Entertainers (actor)
Otto Scheff
(m) 1889-1956
Olympic Medalists 1908 swimming - 400 m freestyle (bronze)
Otto Stern
(m) 1888-1969
Nobel Prize Winners 1943 (physics)
Notable Scientists and Inventors
Otto Stich
(m) 1927-2012
Swiss Presidents 1988; 1994
Otto Strandman
(m) 1875-1941
Estonian Presidents and Prime Ministers 1919; 1929-1931 (prime minister/state elder)
Otto Tief
(m) 1889-1976
Estonian Presidents and Prime Ministers 1944 (prime minister)
Otto Trieloff
(m) 1885-1967
Olympic Medalists 1908 medley relay (silver)
Otto von Bismarck
(m) 1815-1898
German Chancellors and Presidents 1871-1890 (chancellor)
Otto von Guericke
(m) 1602-1686
Notable Scientists and Inventors
Otto Wagner
(m) 1841-1918
Notable Artists
Otto Wahle
(m) 1879-1963
Olympic Medalists 1900; 1904 swimming - 1500 m freestyle; swimming - 200 m obstacle; swimming - 400 m freestyle (silver/bronze)
Otto Wallach
(m) 1847-1931
Nobel Prize Winners 1910 (chemistry)
Notable Scientists and Inventors
Otto Heinrich Warburg
(m) 1883-1970
Nobel Prize Winners 1931 (medicine)
Ruud van Feggelen
(middle name Otto) (m) 1924-2002
Olympic Medalists 1948 water polo (bronze)
Tage Reedtz-Thott
(middle name Otto) (m) 1839-1923
Danish Prime Ministers 1894-1897