Post-World War II museum director and author of the Pelican History of Art volume on northern renaissance sculpture. Müller studied art history between 1923 and 1928 in Germany under such luminaries as Adolph Goldschmidt in Berlin, Heinrich Wölfflin in Zürich, and Wilhelm Pinder in Munich. In 1928 he received his doctorate with a dissertation on the Gothic sculpture of the Tyrol. He joined the Bayerisches Nationalmuseum (Bavarian National Museum) in Munich the same year as an intern, remaining at that sole institution his entire life. His dissertation was published in 1935. From then until 1939 he researched late medieval sculpture, especially in Slovakia, Transylvania and Poland. He became an authority on the work of Veit Stoss. He remained at the Museum throughout the Nazi years in Germany. After World War II, perhaps because of the German-centric ideology imbued in the art-historical German writing before the war, Müller broadened his view to sculpture of France and the Netherlands. Together with the director of the Germanic National Museum in Nuremberg, Erich Steingräber, he wrote a pioneering study on "email en ronde-bosse" around 1400. Together with Adolf Feulner, he authored the second volume of the Deutsche Kunstgeschichte, Geschichte der deutschen Plastik, 1953 He contributed to the festschrift of Wilhelm Pinder. In 1966 he wrote the volume in the distinguished Pelican History of Art series, commissioned by Nikolaus Bernard Leon Pevsner, Sculpture in the Netherlands, Germany, France, and Spain: 1400 to 1500. Unlike some in the series, it was not a work of brilliance, but did set out in an order the disparate work of the period. Müller retired in 1968 from the Museum.Methodologically, Müller's connoisseurship and economy of language owed more the Goldschmidt than to Pinder. Müller's major political accomplishment was to rehabilitate German art history after the Nazi years (Sauerländer).
Die Bildwerke in Holz und Stein von der Mitte des XV. bis gegen Mitte des XVI. Jahrhundertsand. section 2 of Die Bildwerke des Bayerischen Nationalmuseums. Augsburg: B. Filser, 1924ff.; Feulner, Adolf. Geschichte der deutschen Plastik. Deutsche Kunstgeschichte 2. Munich: F. Bruckmann, 1953; and Steingräber, Erich. "Die französische Goldplastik um 1400." Münchner Jahrbuch der bildenden Kunst 5 no. 3 (1954); Sculpture in the Netherlands, Germany, France, and Spain: 1400 to 1500. Pelican History of Art 25. Baltimore: Penguin, 1966;
Sauerländer, Willibald. "Theodor Müller, 1905-96." Burlington Magazine 139, no. 1127 (1997): 109.