Otto is a given name of Germanic origin, including a list of persons and fictional characters with the name.
Otto or otto may also refer to:
- Otto (company), autonomous trucking company
- OTTO Motors, self-driving factory robots
- Otto., Finland's interbank network
- Otto GmbH (Otto Group), a German retail company that operates companies worldwide in the retail, e-commerce, financing, logistics and mail order sectors
- Otto Flugmaschinenfabrik, a 1910s German aircraft manufacturing company
- Otto I, Holy Roman Emperor reigned 962-973
- Otto II, Holy Roman Emperor reigned 973-983
- Otto III, Holy Roman Emperor reigned 996-1002
- 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 (singer), Brazilian singer
- Otto Waalkes, known mononymously as Otto, German comedian
- Otto (surname)
- Otto, Indiana, USA
- Otto, New York, USA
- Otto, North Carolina, USA
- Otto, West Virginia, USA
- Otto, Wyoming, USA
- Otto Township (disambiguation)
- MV Otto, a German coaster
- Operation Otto (1943), Axis powers anti-partisan operation in Croatia in 1943
- Operation Otto (1938), an Axis operational codename for the annexation of Austria
- Otto Celera 500L, an experimental Americal business and utility aircraft built by Otto Aviation
- Otto (dog breed), a breed also known as the Alapaha Blue Blood Bulldog
- Otto (Greyhawk), a wizard in the World of Greyhawk campaign setting for the Dungeons & Dragons roleplaying game
- Otto cycle, the thermodynamic cycle of a typical reciprocating piston engine
- Otto – Der Film, a 1985 German movie
- Otto engine, an early internal combustion engine invented by Nicolaus Otto
- Otto; or Up with Dead People, a 2008 zombie movie
- Otto the Orange, the mascot of Syracuse University
- 2962 Otto, a main-belt asteroid
- 8 (number), Otto in Italian
- Mount Otto, a mountain in Colorado
- Otto, or attar, or ittar any essential oil produced by distillation