Oswald Spengler, German historian and philosopher (d. 1936)
Oswald Arnold Gottfried Spengler (German: [ˈɔsvalt ˈʃpɛŋlɐ]; 29 May 1880 – 8 May 1936) was a German historian and philosopher of history whose interests included mathematics, science, and art and their relation to his organic theory of history. He is best known for his two-volume work, The Decline of the West (Der Untergang des Abendlandes), published in 1918 and 1922, covering all of world history. Spengler's model of history postulates that any culture is a superorganism with a limited and predictable lifespan.

Spengler predicted that about the year 2000, Western civilization would enter the period of pre‑death emergency whose countering would lead to 200 years of Caesarism (extra-constitutional omnipotence of the executive branch of government) before Western civilization's final collapse.

Spengler is regarded as a nationalist and an anti-democrat, and he was a prominent member of the Conservative Revolution. Consequently, he criticised Nazism due to its excessive racism. He saw Benito Mussolini, and entrepreneurial types, like the imperialist mining magnate Cecil Rhodes, as examples of the impending Caesars of Western culture, notwithstanding his stark criticism of Mussolini's imperial adventures.He strongly influenced other historians, including Franz Borkenau and especially Arnold J. Toynbee and other successors including Francis Parker Yockey, Carroll Quigley, and Samuel P. Huntington. John Calvert notes that Spengler is popular with Islamists, who mobilize his critique of the West.