Otto Eduard Leopold, Prince of Bismarck, Count of Bismarck-Schönhausen, Duke of Lauenburg (/ˈbɪzmɑːrk/; born Otto Eduard Leopold von Bismarck-Schönhausen; 1 April 1815 – 30 July 1898) was a German statesman and diplomat who oversaw the unification of Germany and served as its first chancellor from 1871 to 1890. Bismarck's Realpolitik and firm governance resulted in his being popularly known as the Iron Chancellor (Eiserner Kanzler).

From Junker landowner origins, Otto von Bismarck rose rapidly in Prussian politics under King Wilhelm I of Prussia. He served as the Prussian ambassador to Russia and France and in both houses of the Prussian parliament. From 1862 to 1890, he held office as the minister president and foreign minister of Prussia. Under Bismarck's leadership, Prussia provoked three short, decisive wars against Denmark, Austria, and France. After Austria's defeat in 1866, he replaced the German Confederation with the North German Confederation, which aligned the smaller North German states with Prussia while excluding Austria. In 1870, Bismarck secured France's defeat with support from the independent South German states before overseeing the creation of a unified German Empire under Prussian rule. Following Germany's unification, he was given the aristocratic title Prince of Bismarck (Fürst von Bismarck). From 1871 onwards, his balance-of-power approach to diplomacy helped maintain Germany's position in a peaceful Europe. While averse to maritime colonialism, Bismarck acquiesced to elite and popular opinion by acquiring colonies.

As part of his domestic political maneuvering, Bismarck created the first welfare state, with the goal of undermining his socialist opponents. In the 1870s, he allied himself with the low-tariff, anti-Catholic Liberals and fought the Catholic Church, in what was called the Kulturkampf (lit. 'culture struggle'). This failed, with the Catholics responding by forming the powerful German Centre Party and using universal male suffrage to gain a bloc of seats. Bismarck responded by ending the Kulturkampf, breaking with the Liberals and forming a political alliance with the Centre Party to fight the Socialists. Under his direction, the Imperial Reichstag was sidelined and did not control government policy. A staunch monarchist, Bismarck ruled autocratically through a strong bureaucracy with power concentrated in the hands of the Junker elite. After being dismissed from office by Wilhelm II, he retired to write his memoirs.

Otto von Bismarck is most famous for his role in German unification. During the German Imperial period, he became a hero to German nationalists, who built monuments honouring him. Historians praise him as a visionary who kept the peace in Europe through diplomacy. However, he has been criticized for his domestic policies such as his persecution of Catholics as well as his authoritarian rule in general as Chancellor.

Bismarck was born in 1815 at Schönhausen, a noble family estate west of Berlin in Prussian Saxony. His father, Karl Wilhelm Ferdinand von Bismarck (1771–1845), was a Swabian-descendant Junker estate owner and a former Prussian military officer; his mother, Wilhelmine Luise Mencken (1789–1839), was the well-educated daughter of a senior government official in Berlin whose family produced many civil servants along with academics. In 1816, the family moved to its Pomeranian estate, Kniephof (now Konarzewo, Poland), northeast of Stettin (now Szczecin), in the then-Prussian province of Farther Pomerania. There, Bismarck spent his childhood in a bucolic setting. Despite the assets they held, their financial affairs were average; Ferdinand's below adequate agricultural skills led to a decreased salary, with Bismarck having never obtained any significant wealth before unification, given the lack of such received from his father.

Bismarck had two siblings: his older brother Bernhard (1810–1893) and his younger sister Malwine (1827–1908). Others saw Bismarck as a typical backwoods Prussian Junker, an image that he encouraged by wearing military uniforms. However, he was well educated and cosmopolitan with a gift for conversation. Bismarck also knew English, French, Italian, Polish, and Russian.

Bismarck was educated at Johann Ernst Plamann's elementary school, and the Friedrich-Wilhelm and Graues Kloster secondary schools. From 1832 to 1833, he studied law at the University of Göttingen, where he was a member of the Corps Hannovera, and then enrolled at the University of Berlin (1833–1835). In 1838, while stationed as an army reservist in Greifswald, he studied agriculture at the University of Greifswald. At Göttingen, Bismarck befriended the American student John Lothrop Motley. Motley, who later became an eminent historian and diplomat while remaining close to Bismarck, wrote a novel in 1839, Morton's Hope, or the Memoirs of a Provincial, about life in a German university. In it he described Bismarck as a reckless and dashing eccentric, but also as an extremely gifted and charming young man.

Although Bismarck hoped to become a diplomat, he started his practical training as a lawyer in Aachen and Potsdam, and soon resigned, having first placed his career in jeopardy by taking unauthorised leave to pursue two English girls: first Laura Russell, niece of the Duke of Cleveland, and then Isabella Loraine-Smith, daughter of a wealthy clergyman. In 1838, Bismarck began a shortened compulsory military service in the Prussian Army; actively serving as a one-year volunteer before becoming an officer in the Landwehr (reserve). Afterwards he returned to run the family estates at Schönhausen on his mother's death in his mid-twenties.