Theodor Adorno was a member of the Frankfurt School.
The best introduction to Adorno's thought is Adorno's lectures: patient and expansive, they provide the darkest corners of his thought with light and air. Aiming to elaborate the basic assumptions and working method behind his philosophical practice in general, these lapidary lectures touch on many of the most difficult aspects of Adorno's philosophy. J. M. Bernstein, New School for Social Research