Justin K. Thannhauser (1892–1976) was the son of art dealer Heinrich Thannhauser (1859–1935), who founded the Moderne Galerie in Munich in 1909. From an early age, Thannhauser worked alongside his father in the flourishing gallery and helped to build an impressive and versatile exhibition program that included the French Impressionists and Post-Impressionists, the Italian Futurists, and regularly featured contemporary German artists. The Moderne Galerie hosted the premier exhibitions of the New Artists’ Association of Munich (Neue Künstlervereinigung München) and The Blue Rider (Der Blaue Reiter), both of which included Vasily Kandinsky, in 1909 and 1911, respectively. Kandinsky later described the gallery’s rooms as “perhaps the most beautiful exhibition spaces in all of Munich.” The Moderne Galerie also mounted one of the first major Pablo Picasso retrospectives in Germany in 1913, thus initiating the close relationship between Justin K. Thannhauser and Picasso that lasted until the artist’s death in 1973.

An ambitious businessman, Thannhauser opened a second gallery in Lucerne in 1919 with his cousin Siegfried Rosengart (1894–1985). Eight years later, the highly successful Galleries Thannhauser—as the Munich and Lucerne branches were collectively called—tested the waters in Berlin with a major special exhibition before permanently relocating its Munich gallery to this thriving art center. The Galleries Thannhauser officially closed in 1937, shortly after Thannhauser and his family immigrated to Paris. Thannhauser eventually settled in New York in 1940 and, together with his second wife, Hilde (1919–91), established himself as a private art dealer.

The Thannhausers’ commitment to promoting artistic progress paralleled the vision of Solomon R. Guggenheim (1861–1949). In appreciation of this shared spirit, and in the memory of his first wife and two sons—who might have continued in the family’s art trade had they not died at tragically young ages—Thannhauser gave a significant portion of his art collection, including over 30 works by Picasso, to the Solomon R. Guggenheim Foundation in 1963. From 1965 until Thannhauser’s death in 1976 (when his collection formally entered the Guggenheim’s holdings), the Thannhauser Collection was on long-term loan to the museum. A bequest of 10 additional works received after Hilde Thannhauser’s death in 1991 enhanced the legacy of this family of important art dealers.