Theodor W. Adorno (September 11, 1903 – August 6, 1969) was a German sociologist, philosopher and musicologist known for his critical theory of society.

He was a leading member of the Frankfurt School of critical theory, whose work has come to be associated with thinkers such as Ernst Bloch, Walter Benjamin, Max Horkheimer and Herbert Marcuse, for whom the work of Freud, Marx and Hegel were essential to a critique of modern society. He is widely regarded as one of the 20th century's foremost thinkers on aesthetics and philosophy, as well as one of its preeminent essayists. As a critic of both fascism and what he called the culture industry, his writings—such as Dialectic of Enlightenment (1947), Minima Moralia (1951) and Negative Dialectics (1966)—strongly influenced the European New Left.

Walter Bendix Schönflies Benjamin (German pronunciation: [ˈvaltɐ ˈbɛnjamiːn]; 15 July 1892 – 26 September 1940) was a German-Jewish literary critic, philosopher, social critic, translator, radio broadcaster and essayist. Combining elements of German idealism or Romanticism, Historical Materialism and Jewish mysticism, Benjamin made enduring and influential contributions to aesthetic theory and Western Marxism, and has sometimes been associated with the Frankfurt School of critical theory. Among his major works as a literary critic are essays on Goethe's novel Elective Affinities; the work of Franz Kafka and Karl Kraus; translation theory; the stories of Nikolai Leskov; the work of Marcel Proust and perhaps most significantly, the poetry of Charles Baudelaire. He also made major translations into German of the Tableaux Parisiens section of Baudelaire's Les Fleurs du mal and parts of Proust's À la recherche du temps perdu.

His turn to Marxism in the 1930s was partly due to the influence of Bertolt Brecht, whose critical aesthetics developed epic theatre and its Verfremdungseffekt (defamiliarisation, alienation). An earlier influence was friend Gershom Scholem, founder of the academic study of the Kabbalah and of Jewish mysticism.

Max Horkheimer (February 14, 1895 – July 7, 1973) was a German-Jewish philosopher-sociologist, famous for his work in critical theory as a member of the 'Frankfurt School' of social research. His most important works include The Eclipse of Reason (1947) and, in collaboration with Theodor Adorno, The Dialectic of Enlightenment (1947). Through the Frankfurt School, Horkheimer planned, supported and made other significant works possible.

Horkheimer was born in the Zuffenhausen district of Stuttgart, then capital of the Kingdom of Württemberg within the German Empire, to a wealthy Jewish family. Due to parental pressure, Horkheimer left secondary school at the age of sixteen to work in his father's factory. In 1916, his manufacturing career ended and he was drafted into World War I. After World War I, he enrolled at Munich University, where he studied philosophy and psychology. After university, Horkheimer moved to Frankfurt am Main, where he studied under Hans Cornelius. There, he met Theodor Adorno, several years his junior, with whom he would strike a lasting friendship and a fruitful collaborative relationship.