German diplomat who married the heiress of the Krupp family of industrialists, Bertha Krupp, and took over operation of the family firm. At the time of their wedding, the Krupp name was added to his own.

Bertha's father, Friedrich Krupp, committed suicide in scandal in 1902, having been exposed in the newspapers as a homosexual. Because it was deemed unthinkable for the Krupp armament empire to be run by a woman, the emperor William II personally sought an acceptable husband for the young Bertha (1886–1957), eventually choosing Gustav von Bohlen und Halbach, a Prussian diplomat. They were married on Oct. 15, 1906, and Gustav was authorized by the emperor to add the name Krupp to his own.

In World War I, Gustav Krupp made many contributions to Germany's arsenal. One was the 98-ton howitzer that shelled Liège and Verdun. Others included the great cannon that bombarded Paris from a range of about 75 miles (120 km) and Germany's submarines, which were built at the family's Kiel shipyards. Because Germany was defeated, the war was, on the whole, bad business for Krupp but not a total loss. Before the war, in 1902, Vickers, Ltd., a British manufacturer of artillery shells, had leased a Krupp fuse patent. After the war, Vickers paid off in a settlement based on German artillery casualties, which placed Krupp in the awkward position of having profited from Germany's war dead.

With this money, and with subsidies from the government of the Weimar Republic, Gustav began the secret rearming of Germany within a year of the Armistice. In his words, he was determined that Krupp should be ready “again to work for the German armed forces at the appointed hour without loss of time or experience.” Submarine pens were furtively built in Holland; new cannon were covertly perfected in Sweden. Krupp helped finance the Nazi (Nazi Party) “terror election” of 1933, tightening Adolf Hitler's grip on the reins of government, and, as president of the Reichsverband der Deutschen Industrie—Germany's equivalent of the U.S. Chamber of Commerce—expelled all Jewish industrialists and became one of the country's most ardent Nazis.

Growing senile, Gustav was succeeded by his son Alfried in 1943. After the war the Allies proposed to indict Gustav as a war criminal for his part in Germany's armament, but in view of his ill health he was never brought to trial.