Otto is a given name of Germanic origin meaning wealthy.
- 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
- the Ottonian dynasty
- Otto IV, Holy Roman Emperor (1175/1176-1218)
- Otto Dowling (1881-1946), 25th Governor of American Samoa
- Otto of Freising (c. 1114-1158), bishop and chronicler
- Otto of Greece (1815-1867), King of Greece
- Otto of Bavaria (1848-1916), King of Bavaria
- Otto Adler, president of the Jewish Association of Romania
- Otto Frank (1889–1980), 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 Herschmann (1877–1942), Austrian Olympic fencing and swimming medalist
- Otto Knows Swedish DJ
- Otto Klemperer (1885-1973), German-born conductor and composer
- Otto Kretschmer (1912 – 1998), German WWII U-Boat Captain
- Otto Lilienthal, German aviator
- Otto Peterson, American comedian (Otto & George ventriloquism act)
- Otto Plath (1885-1940), father of American Poet, Sylvia Plath, and entomologist
- Otto Preminger (1905-1986), Austro–Hungarian-born American film director
- Otto Rehhagel, German football coach
- Otto Scheff, Austrian Olympic swimming champion
- Otto Schmitt (field hockey), Argentine field hockey goalkeeper
- Otto Skorzeny (1908-1975), Austrian-born Waffen-SS commando
- Otto Soglow, American cartoonist
- 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 Wahle (1879-1963), Austrian-born American Olympic swimming medalist and Hall of Fame
- Otto Weininger (1880-1903), Christian Austrian philosopher
- Otto Dix (1891-1969), German painter and printmaker, noted for his ruthless and harshly realistic depictions of Weimar society and the brutality of war.
- Otto Flick, a character in the BBC sitcom 'Allo 'Allo!
- Otto Maddox, a character in the movie Repo Man, played by Emilio Estevez.
- Otto Mann, character on the animated TV series The Simpsons.
- Otto Meyer, a character in the 1963 movie It's a Mad, Mad, Mad, Mad World, played by Phil Silvers.
- Otto Normalverbraucher, a home coming soldier in a 1948 movie played by Gert Fröbe, is used in German to denote the average consumer (literally) or the small man on the street
- Otto Octavius, fictional Marvel Comics supervillain otherwise known as Doctor Octopus. One of Spider-Man's nemeses.
- Otto, Gothel's pet talking ferret in the 2002 direct-to-video Barbie film Barbie as Rapunzel, voiced by Peter Kelamis.
- Otto Rocket, the main character of Nickelodeon's Rocket Power.
- Otto the Dog, a dog belonging to one of the characters in the comic strip Beetle Bailey.
- Otto the Gorilla, Dr Satan's fretful right hand man in Rob Zombie's satire comedy The Haunted World of El Superbeasto
- Otto the Autopilot, the blow-up autopilot doll in Airplane! (1980)
- Otto West, a character in the 1988 movie A Fish Called Wanda.
- Otto Malpense, the main character in the H.I.V.E. series by Mark Walden
- Otto Delaney, a character in the drama Sons of Anarchy on the American TV network FX, played by series creator Kurt Sutter.