Alfred Baeumler (1887–1968), German philosopher in Nazi Germany. He was a leading interpreter of Friedrich Nietzsche's philosophy as legitimizing Nazism. Thomas Mann read Baeumler's work on Nietzsche in the early 1930s, and characterized passages of it as "Hitler prophecy."
Martin Heidegger (1889–1976), German philosopher who was politically involved with National Socialism. The relations between Martin Heidegger and Nazism remain controversial. He was a member of the Nazi party, he joined the NSDAP on May 1, 1933 three weeks after being appointed rector of the University of Freiburg. Heidegger resigned the rectorship one year later, in April 1934, but remained a member of the NSDAP until the end of World War II. His first act as rector was to eliminate all democratic structures, including those that had elected him rector. There were book burnings on his campus, though he successfully stopped some of them. There was also student violence.
Carl Schmitt (11 July 1888 – 7 April 1985) was a jurist, philosopher, political theorist, and professor of law. Schmitt joined the Nazi Party on 1 May 1933. He presented his theories as an ideological foundation of the Nazi dictatorship, and a justification of the "Führer" state with regard to legal philosophy, in particular through the concept of auctoritas. Nevertheless, in December 1936, the SS publication Das schwarze Korps accused Schmitt of being an opportunist, a Hegelian state thinker and basically a Catholic, and called his anti-semitism a mere pretense, citing earlier statements in which he criticized the Nazis' racial theories. After this, Schmitt resigned from his position as "Reichsfachgruppenleiter" (Reich Professional Group Leader), although he retained his post as a professor in Berlin, and his post as "Preußischer Staatsrat". Although Schmitt continued to be investigated into 1937, further reprisals were stopped by Göring. In 1945, Schmitt was captured by the American forces and released in 1946. Schmitt refused every attempt at de-nazification, which effectively barred him from positions in academia.
Hans Friedrich Karl Günther (1891–1968), German race researcher and eugenicist in the Weimar Republic and the Third Reich, also known as "Rassengünther" (Race Günther) or "Rassenpapst" (Race Pope). He is considered to be a major influence on National Socialist racialist thought, and was a member of the Nazi Party.
Alfred Ploetz (1860–1940), German physician, biologist, and eugenicist who introduced the concept of racial hygiene in Germany. He was a member of the Nazi party. His brother Ernst Rüdin, also a committed National Socialist, praised him in 1938 as a man who "by his meritorious services has helped to set up our Nazi ideology."
Ernst Bergmann (1881–1945), German philosopher who in his work, Die 25 Thesen der Deutschreligion (Twenty-five Points of the German Religion), held that the Old Testament and portions of the New Testament of the Bible were inaccurate. He claimed that Jesus was not a Jew and of Aryan origin, and that Adolf Hitler was the new messiah.
Savitri Devi, pseudonym of the Greek-French writer Maximiani Portas. A prominent proponent of animal rights, deep ecology and Nazism, who served the Axis cause during World War II by spying in India.
Ludwig Müller (1883–1945), was a theologian and church leader who played a major role in the Nazi party's attempt to misdirect the Protestant, mainly Lutheran churches of Germany toward a basis in Aryan ideology and away from its Jewish origins. He had a leading part in the Nazi, Gleichschaltung, the plan to unite the previously independent Protestant churches into a single Church of the New Order, which is part of longer history of an attempt to unify the churches under the German Evangelical Church, see Reichskirche. Withholding baptism from non-Aryans was enforced in most churches during the Nazi period, though not without some protest.
Anton Drexler (1884–1942), German Nazi political leader of the 1920s. He joined the Fatherland Party during World War I. He was a poet and a member of the völkisch agitators who, together with journalist Karl Harrer, founded the German Workers' Party (DAP) in Munich with Gottfried Feder and Dietrich Eckart in 1919.
Gottfried Feder (1883–1941), economist and one of the early key members of the Nazi party. He was their economic theoretician. It was his lecture in 1919 that drew Hitler into the party.
Gottlob Frege (1848–1925) was a German mathematician, logician and philosopher. He is considered to be one of the founders of modern logic and made major contributions to the foundations of mathematics. He is generally considered to be the father of analytic philosophy, for his writings on the philosophy of language and mathematics. Frege confided "that he had once thought of himself as a liberal and was an admirer of Bismarck, but his heroes now were General Ludendorff and Adolf Hitler. This was after the two had tried to topple the elected democratic government in a coup in November 1923. In his diary Frege also used all his analytic skills to devise plans for expelling the Jews from Germany and for suppressing the Social Democrats."
Gregor Strasser (1892–1934) Involved in the Kapp Putsch he formed his own völkischer Wehrverband ("popular defense union") which he merged into the NSDAP in 1921. Initially a loyal supporter of Adolf Hitler, he took part in the Beer Hall Putsch and held a number of high positions in the Nazi Party. Soon however, Strasser became a strong advocate of the socialist wing of the party, arguing that the national revolution should also include strong action to tackle poverty and should seek to build working class support.
Julius Streicher (1885–1946), the founder and publisher of Der Stürmer newspaper, which became a central element of the Nazi propaganda machine. His portrayal of Jews as subhuman and evil played a critical role in the dehumanization and marginalization of the Jewish minority in the eyes of common Germans – creating the necessary conditions for the later perpetration of the Holocaust. He was a member of the Nazi party.
Intellectuals indirectly associated with Nazism
Some writers came before the Nazi era and their writings were (sometimes falsely) incorporated into Nazi ideology:
Madame Blavatsky (1831–1891), founder of Theosophy and the Theosophical Society. Guido von List took up some of Blavatsky's racial theories, and mixed them with nationalism to create Ariosophy, a precursor of Nazi ideology. Ariosophy emphasized intellectual expositions of racial evolution. The Thule Society was one of several German occult groups drawing on Ariosophy to preach Aryan supremacy. It provides a direct link between occult racial theories and the racial ideology of Hitler and the emerging Nazi party.
Houston Stewart Chamberlain (1855–1927) was a British-born author of books on political philosophy, and natural science. His two-volume book Die Grundlagen des Neunzehnten Jahrhunderts (Foundations of the 19th. Century) (1899) became a manual for Nazi racial philosophy including the concept of the master race.
Julius Evola (1898–1974), a philosopher described as an "ultra-fascist" with an interest in the occult and Eastern religions-->
Hans Freyer (1887–1969), German sociologist who called for an anti-liberal, anti-materialist, anti-Marxist Revolution von rechts (Revolution from the Right) that would emphasize organic bonds and community (Gemeinschaft) over the atomization of industrialized society (Gesellschaft).
Martin Luther (1483–1546), German theologian who wrote On the Jews and Their Lies in 1543. He argued that the Jews were "devil's children". He wrote that the synagogue was a "defiled bride ... an incorrigible whore and an evil slut". and Jews were full of the "devil's feces ... which they wallow in like swine." He advocated setting synagogues on fire, destroying Jewish prayerbooks, forbidding rabbis from preaching, seizing Jews' property and money, smashing up their homes, and ensuring that these "poisonous envenomed worms" be forced into labor or expelled "for all time." He also seemed to sanction their murder, writing "We are at fault in not slaying them." His statements that Jews' homes should be destroyed, their synagogues burned, money confiscated and liberty curtailed were revived and used in propaganda by the Nazis in 1933–1945. Some scholars see Luther's influence as limited, and the Nazis' use of his work as opportunistic. Johannes Wallmann argues that Luther's writings against the Jews were largely ignored in the 18th and 19th centuries, and that there is no continuity between Luther's thought and Nazi ideology.
Friedrich Nietzsche (1844–1900), German philosopher who developed the concept of Übermensch. The Nazi regime's ideas of the German superman were similar to those expressed by Nietzsche. However, it seems that Hitler probably never read Nietzsche, or if he did, the reading was not extensive.
Oswald Arnold Gottfried Spengler (1880–1936), German historian and philosopher. He is best known for his book The Decline of the West and the cyclical theory of the rise and decline of civilizations. He wrote extensively throughout World War I and the interwar period, and supported German hegemony in Europe. The National Socialists held Spengler as an intellectual precursor but he was ostracized after 1933 for his pessimism about Germany and Europe's future, and his refusal to support Nazi ideas of racial superiority.
Adolf Stoecker (1835–1909), court chaplain to Kaiser Wilhelm and an antisemitic German theologian who founded one of the first antisemitic political parties in Germany, the Christian Social Party. He proposed severely limiting the civil rights of Jews in Germany. In September 1879 he delivered a speech entitled "What we demand of modern Jewry", in which he spelled out several demands of German Jews.
Georges Vacher de Lapouge (1854–1936), French anthropologist, eugenicist, and anti-semite who developed the idea of a "Selectionist State" that would implement coercive measures to maintain the dominance and purity of dolichocephalic Aryans. His work strongly influenced Nazi eugenicists such as Hans F. K. Günther.
^Bendersky, Joseph, W., Theorist For The Reich, 1983, Princeton, New Jersey
^Noack, Paul, Carl Schmitt - Eine Biographie, 1996, Frankfurt
^Christopher Hale. Himmler's Crusade: the True Story of the 1938 Nazi Expedition into Tibet Bantam, 2004. ISBN 978-0-553-81445-3
^"Die Tüchtigkeit unserer Rasse und der Schutz der Schwachen", 1893, p. 141, 142. cited by Massimo Ferari Zumbini: The roots of evil. Gründerjahre des Antisemitismus: Von der Bismarckzeit zu Hitler, Vittorio Klostermann, Frankfurt a. M. 2003, ISBN 3-465-03222-5, p.406
^Ernst Ruedin: "Honor of Prof. Dr. Alfred Ploetz", in ARGB, Bd 32 / S.473-474, 1938, p.474
^McNab, Chris (2009). The Third Reich. Amber Books Ltd., p. 182
^Kenneth Barnes, "Nazism, Liberalism and Christianity", University Press of Kentucky, Kentucky 1991.
^"Dietrich Eckart". Jewish Virtual Library. Retrieved 2009-01-04. Later on, he developed an ideology of a 'genius higher human,' based on earlier writings by Lanz von Liebenfels; he saw himself in the tradition of Arthur Schopenhauer and Angelus Silesius, and also became fascinated by Mayan beliefs, but never had much sympathy for the scientific method. Eckart also loved and strongly identified with Henrik Ibsen's Peer Gynt.
^Nazi Ideology: Some Unfinished Business - BM Lane - Central European History, 1974 - jstor.org 
^Munich 1923, John Dornberg, Harper & Row, New York, 1982. pg 344
^Henry Friedlander (1977). The Holocaust: Ideology, Bureaucracy, and Genocide. Gottfried Feder gave technocratic ideology a racist twist. ... arouses interest because he helped to shape Nazi ideology during the early 1920's. ...
^Dummett, Michael, 1973. Frege: Philosophy of Language. Harvard University Press.
^The Number One Nazi Jew-baiter: A Political Biography of Julius Streicher, Hitler's Chief Anti- … WP Varga - 1981 - Carlton Press
^Stern, Fritz The Politics of Cultural Despair: a study in the Rise of the Germanic Ideology, 1961 (see Chapter I, "Paul de Lagarde and a Germanic Religion").
^Michael, Robert. Holy Hatred: Christianity, Antisemitism, and the Holocaust. New York: Palgrave Macmillan, 2006, p. 110.
^Martin Luther (1543). On the Jews and their Lies. Our Lord also calls them a "brood of vipers"; furthermore in John 8 [:39,44] he states: "If you were Abraham's children ye would do what Abraham did.... You are of your father the devil. It was intolerable to them to hear that they were not Abraham's but the devil's children, nor can they bear to hear this today.
^Michael, Robert. Holy Hatred: Christianity, Antisemitism, and the Holocaust. New York: Palgrave Macmillan, 2006, p. 112.
^Obermann, Heiko. Luthers Werke. Erlangen 1854, 32:282, 298, in Grisar, Hartmann. Luther. St. Louis 1915, 4:286 and 5:406, cited in Michael, Robert. Holy Hatred: Christianity, Antisemitism, and the Holocaust. New York: Palgrave Macmillan, 2006, p. 113.
^Luther, Martin. "On the Jews and Their Lies", Luthers Werke. 47:268-271.
^Michael, Robert. "Luther, Luther Scholars, and the Jews", Encounter, 46 (Autumn 1985) No.4:343.
^Luther, Martin. On the Jews and Their Lies, cited in Michael, Robert. "Luther, Luther Scholars, and the Jews", Encounter 46 (Autumn 1985) No. 4:343-344.
^McKim, Donald K. (ed.) The Cambridge Companion to Martin Luther. New York: Cambridge University Press, 2003, 58; Berenbaum, Michael. "Anti-Semitism", Encyclopaedia Britannica, accessed January 2, 2007. For Luther's own words, see Luther, Martin. "On the Jews and Their Lies", tr. Martin H. Bertram, in Sherman, Franklin. (ed.) Luther's Works. Philadelphia: Fortress Press, 1971, 47:268–72.
^Johannes Wallmann, "The Reception of Luther's Writings on the Jews from the Reformation to the End of the 19th century", Lutheran Quarterly, n.s. 1 (Spring 1987) 1:72-97.
^The Nietzsche Legacy in Germany: 1890-1990 - SE Aschheim - 1992 - University of California Press - ISBN 0520085558
^Weaver Santaniello, Nietzsche, God, and the Jews,SUNY Press, 1994, p 41: "Hitler probably never read a word of Nietzsche".
^Berel Lang, Post-Holocaust: Interpretation, Misinterpretation, and the Claims of History, Indiana University Press, 2005, p 162: "Arguably, Hitler himself never read a word of Nietzsche; certainly, if he did read him, it was not extensively".
^Golomb 1997, p. 9: "To be sure, it is almost certain that Hitler either never read Nietzsche directly or read very little."
^Andrew C. Janos, East Central Europe in the Modern World,Stanford University Press, 2002, p 184: "By all indications, Hitler never read Nietzsche. Neither Mein Kampf nor Hitler's Table Talk (Tischgesprache) mentions his name. Nietzschean ideas reached him through the filter of Alfred Rosenberg's Myth of the Twentieth Century, and...through what was coffeehouse Quatsch in Vienna and Munich. This at least is the impression he gives in his published conversations with Dietrich Eckart."
^Journal of Church and State - JC Fout - Adolf Stoecker Antisemitism – 1975.