List of military / O

If

O'Bannon, Presley (1776–1850), US Marine Corps officer; famous for his actions during the American Tripolitan War; he was presented with a Mamluk sword in recognition and every American Marine officer has carried one since then
Obernitz, Hugo von (1819–1901), Prussian general; Adjutant General of Kaiser Wilhelm I.
Obilić, Miloš , († 1389), Serbian knight and hero
Obregón, Álvaro (1880–1928), Mexican general, President of Mexico 1920–1924
Obrenović, Miloš , (1783–1860) leader of the Second Serbian uprising against the Ottomans (1815)

Odierno, Raymond T. (* 1954), American Lieutenant General, Commanding General of the III. US Corps in Iraq since December 2006
O'Donnell, Karl , Count of Tyrconnel, (1715–1771), Austrian general in the Seven Years War
O'Donnell, Maximilian Karl Lamoral , Count of Tyrconnel, (1812–1895), Austrian Lieutenant Field Marshal
O'Donnell, Joseph Heinrich , Count of Abispal, (1769–1834), Spanish general in the fight against Napoleon; Captain General of Andalusia; Governor of Cadiz
O'Donnell, Leopoldo , Earl of Lucena, Duke of Tetuan, (1809-1867); Spanish general and statesman
O'Donojú, Juan (1762–1821), Spanish lieutenant general and the last viceroy of New Spain
Odumegwu, Chukwuemeka (1933–2011), Nigerian officer and politician

Ogilvy, Georg Benedikt Freiherr von (1651–1710), Field Marshal General of the Electorate of Saxony
Ogle, Chaloner (1681-1750), British admiral; successful in fighting the pirates

O'Higgins, Bernardo (1778–1842), leader of the Chilean army in the struggle for independence; Chile's first head of state

Olbricht, Friedrich (1888–1944), German general and resistance fighter of July 20; shot dead
Oldendorf, Jesse B. (1887–1974), American admiral in the Pacific War; known for his victory in the sea and air battles in the Gulf of Leyte
Olfermann, Johann Elias (1776–1822), Braunschweig major general; Participants in the Wars of Liberation
Ollech, Karl Rudolf von (1811–1884), Prussian general; war history writer
Olshausen, Klaus (* 1945), German lieutenant general in the Bundeswehr; President of the Clausewitz Society
Olson, Eric T. (born 1952), American admiral; deputy commander of the US Special Operations Command

Aleš Opata (* 1964), Czech officer
Oppeln-Bronikowski, Hermann von (1899–1966), German Olympic champion in dressage (1936); Major General and Commander in World War II
Oppeln-Bronikowski, Johann von (1679–1765), Prussian major general, knight of the order Pour le Mérite
Oppeln-Bronikowski, Karl Ludwig von (1766–1842), member of the Military Reorganization Commission; Commander of the Erfurt Fortress

Orange, Friedrich Heinrich von (1584–1647), 1625–1647 governor of the Netherlands, general ("Städtebezwinger")
Orange, Moritz von , Count of Nassau-Dillenburg, (1567–1625), Captain General of the Land and Naval Forces of the United Netherlands
Orange, Wilhelm I. von , Count of Nassau-Dillenburg, (1533–1584), general, leader in the Dutch struggle for independence
Orange, Wilhelm III. von (1650–1702) general, governor of the Netherlands, king of England, Scotland and Ireland
Ordener, Michel (1755–1811), Napoleonic general
Orléans, Philip II, Duke of (1674–1723), Regent of France
Orlow, Alexei Grigoryevich (1737–1808), Russian general and admiral; Murderer Tsar Peters III.
Orlow, Grigori Grigoryevich (1734–1783), Russian general and lover of Catherine the Great
Orlow, Alexei Fjodorowitsch (1786–1861), Russian general and statesman
Orlow, Nikolai Alexejewitsch (1820–1885), Russian officer and diplomat
Ornano, Alphonse de (1548–1610), French military leader of Corsican descent; 1595 Marshal of France
Ornano, Philippe-Antoine de (1784–1863), French general; Marshal of France

Osman Digna (1836–1926), general in the Mahdi army in Sudan
Osman Nuri Pascha , the "Lion of Plevna", (1837–1900), Turkish general in the Russo-Turkish War; 1878 Minister of War
Osten-Sacken, Dmitri Erofejewitsch (1790 / 1793–1881), Russian general of the cavalry
Osten-Sacken, Fabian Gottlieb von der (1752–1837), Russian field marshal
Oster, Hans (1887–1945), German major general; Chief of Staff of the Military Defense and Resistance Fighters; executed
Ostermann-Tolstoy, Alexander Iwanowitsch (1790–1857), Russian general
Austria, Archduke Albrecht von (1817–1895), Austrian field marshal; Governor General and Commanding General in Hungary; Inspector General of the Army
Austria, Archduke Eugen von (1863–1954), Grand Master of the Teutonic Order; Field marshal; Commander of the South-Western Front in World War I.
Austria, cardinal- infant Ferdinand von (1609–1641), cardinal and general in the Thirty Years War

Austria, Archduke Karl von , Duke of Teschen, (1771–1847), Austrian general; President of the Court War Council; Army reformer

Austria, Karl Albrecht von (1888–1951), Austrian (kuk) colonel and Polish general and landowner.

Austria, Archduke Leopold Wilhelm von (1614–1662), general and governor of the Spanish Netherlands

Austria, Archduke Wilhelm von (1827-1894), Austrian field military officer

Austria, Archduke Rainer von (1827–1913), old Austrian general

Austria-Este, Archduke Ferdinand Karl von (1781–1850), Field Marshal and Governor General of Galicia and Transylvania

Austria-Este, Archduke Maximilian Joseph von (1782–1863), Austrian specialist in artillery and fortifications; Grand Master of the Teutonic Order

Ott von Bátorkéz, Karl Freiherr (1738–1809), Austrian Lieutenant Field Marshal
Otter, Fredrik Wilhelm von (1833-1910), Swedish admiral; Head of the Swedish Navigation Authority; Prime Minister
Otto, Wolfgang , (* 1947), Lieutenant General in the Bundeswehr; Commander of the Army Command

Oudinot, Nicolas-Charles , duc de Reggio, (1767–1847), Napoleonic general; Marshal of France
Oudinot, Nicolas-Charles-Victor , 2nd Duke of Reggio, (1791–1863), French general; Son of the previous one
Outram, James (1803–1863) British general in India

Ozawa, Jisaburō (1886-1966), Japanese admiral; last Commander in Chief of the Imperial Japanese Navy in World War II