Medieval period •
Otto (mayor of the palace) (died 643 or 644), mayor of the palace of
Austrasia briefly in the mid-7th century •
Otto I, Duke of Saxony (851–912) •
Otto the Great (912–973), East Frankish king and Holy Roman Emperor •
Otto II, Holy Roman Emperor (955–983) •
Otto III, Holy Roman Emperor (980–1002) •
Otto IV, Holy Roman Emperor (1175/1176–1218) •
Otto, Count of Cleves (1278–1310) •
Otto, Count of Lippe-Brake (1589–1657) •
Otto, Duke of Lolland and Estonia (1310–1346) •
Otto, Count of Looz (fl. 980-1000) •
Otto, Count of Vermandois (979–1045) •
Otto, Landgrave of Hesse-Kassel (1594–1617) •
Otto, Lord of Arkel (1330–1396) •
Otto, Lord of Lippe (1300–1360) •
Otto, Margrave of the Nordmark (died 1057) •
Otto of Bamberg (1060/1061–1139), bishop and Catholic saint •
Otto of Freising (c. 1114–1158), bishop and chronicler
Modern era •
Otto of Greece (1815–1867), King of Greece •
Otto, King of Bavaria (1848–1916), King of Bavaria •
Otto Adler (1929–2014), president of the Jewish Association of Romania •
Otto T. Bannard (1854–1929), American attorney, businessman and philanthropist •
Otto Barić (1933–2020), Croatian footballer and manager •
Otto Brandenburg (1934–2007), Danish musician, singer and actor •
Otto Carius (1922–2015), German tank ace and pharmacist •
Otto Diels (1876–1954), German chemist •
Otto Dix (1891–1969), German painter and printmaker •
Otto Dowling (1881–1946), governor of American Samoa •
Otto Eloluoto (born 2008), Finnish footballer •
Otto Fahlgren (born 2001), Swedish actor •
Otto Farrant (born 1996), British actor •
Otto Fischer (footballer) (1901–1941), Austrian football player and coach •
Otto Floto (1863–1929), American sports journalist •
Otto Förschner (1902–1946), German Nazi SS concentration camp commandant •
Otto Frank (1889–1980), German-born Swiss businessman, father of Anne Frank •
Otto Freundlich (1878–1943), German painter and sculptor •
Otto Graham (1921–2003), professional American football and basketball player •
Otto Graf Lambsdorff (1926–2009), German politician •
Otto Grotewohl (1894–1964), East German politician •
Otto Gutekunst (1866–1947), British art dealer •
Otto Hahn (1879–1968), German chemist •
Otto Hautamo (born 2002), Finnish footballer •
Otto Herschmann (1877–1942), Austrian fencer and swimmer •
Otto Hindrich (born 2002), Romanian footballer •
Otto Kemp (born 1999), American baseball player •
Otto Kemppainen (born 2003), Finnish footballer •
Otto Klemperer (1885–1973), German-born conductor and composer •
Otto Knows (born 1989), Swedish DJ •
Otto Koivula (born 1998), Finnish ice hockey player •
Ottó Komoly (1892–1945) Hungarian humanitarian, engineer, officer and Zionist •
Otto Kraushaar (1901–1989), American academic •
Otto Kretschmer (1912–1998), German World War II U-boat captain •
Otto Lehtisalo (born 2004), Finnish footballer •
Otto Lietchen (1887–1977), American politician •
Otto Lilienthal (1848–1896), German aviator •
Otto Ludvig Beckman (1856–1909), Swedish major general •
Otto Lybeck (1871–1947), Swedish Navy admiral •
Otto Mahler (1873–1895), Bohemian-Austrian composer, brother of Gustav Mahler •
Otto Mears (1840–1931), Russian-American road and railway builder •
Otto Moll (1915–1946), German SS-Hauptscharführer at Auschwitz concentration camp •
Otto Ohlendorf (1907–1951), German SS general and Holocaust perpetrator •
Otto Maximiliano Pereira de Cordeiro Ferreira (born 1968), Brazilian singer-songwriter, drummer and TV presenter •
Otto Peterson (1960–2014), American comedian •
Otto Petrén (1912–1990), Swedish jurist •
Otto Porter (born 1993), American basketball player •
Otto Planetta (1899–1934), Austrian Nazi Waffen-SS who murdered Austrian Chancellor
Engelbert Dollfuss •
Otto Plath (1885–1940), entomologist, father of American poet
Sylvia Plath •
Otto Pohla (1899–1941), Estonian wrestler •
Otto Preminger (1905–1986), Austro–Hungarian-born American film director •
Otto Rehhagel (born 1938), German football coach •
Otto Ruoppi (born 2006), Finnish footballer •
Otto Sigfrid Reuter (1876–1945), German
völkisch-religious ideologue •
Otto Salmensuu (born 2004), Finnish footballer •
Otto Sauter-Sarto (1884–1958), German actor •
Otto Scheff (1889–1956), Austrian swimmer •
Otto Schily (born 1932), German politician •
Otto Schmitt (field hockey) (born 1965), Argentine field hockey player •
Otto Skorzeny (1908–1975), Austrian-born Waffen-SS commando •
Otto Sohn-Rethel (1877–1949), German painter and lepidopterist •
Otto Soglow (1900–1975), American cartoonist •
Otto Strandman (1875–1941), Estonian politician, Prime Minister in 1919, head of state 1929–1931 •
Otto Tief (1889–1976), Estonian politician, military commander, lawyer, Prime Minister •
Otto Toeplitz (1881–1940), German mathematician, specialized in functional analysis •
Otto van Verschuer (1927–2014), Dutch politician •
Otto Christian Archibald von Bismarck (1897–1975), German politician and diplomat •
Otto von Bismarck (1815–1898), Prussian/German statesman •
Otto von Habsburg (1912–2011), head of the House of Habsburg-Lorraine from 1922 to 2007 •
Otto Waalkes (born 1948), German comedian and actor •
Otto Wagner (1841–1918), Austrian architect •
Otto Wahle (1879–1963), American swimmer •
Otto F. Walter (1928–1994), Swiss journalist, author and publisher •
Otto Warmbier (1994–2017), American student imprisoned in North Korea •
Otto Weininger (1880–1903), Austrian philosopher •
Otto Wichterle (1913–1998), Czech chemist, inventor soft contact lenses •
Otto S. Wolfbeis (1947–2023), German chemist •
Otto the Liar (2006–), Canadian 3 on 3 Hockey Player. Named by Stipe of Zadar. ==Fictional characters==