German banker and industrialist, he was the main shareholder of AGFA, which his father co-founded and which is part of I.G. Farben, and he was a member of the supervisory board of both companies. He was forced out of his company by “Aryanization” and the persecution of the Jews and only barely survived Nazi persecution in Germany.
Otto Mendelssohn Bartholdy was the oldest child of Paul Mendelssohn Bartholdy the Elder and his first wife, Else Mendelssohn Bartholdy (née Oppenheim, 1845–1868). His mother died of typhus five months after Otto was born. Five years after the death of his first wife, his father married her younger sister Enole Oppenheim (1855–1939) in 1873, with whom he had four more children. Otto’s youngest brother from his father’s second marriage was Paul (1879–1956), who, as a doctor of chemistry and AGFA director, was to follow in his father’s footsteps. Their paternal grandfather were the composer Felix Mendelssohn Bartholdy.
On 8 April 1893, Otto Mendelssohn Bartholdy married his two-year-younger cousin Cécile (1870–1943), née Mendelssohn Bartholdy, in Baden-Baden at the age of 25. They had two children, the son Hugo Mendelssohn Bartholdy and the daughter Cécile Mendelssohn Bartholdy, born in Berlin in 1894 and 1898 respectively.
Otto Mendelssohn Bartholdy became an influential banker, first as an authorized signatory, later as a partner in the Berlin private bank Robert Warschauer & Co. In 1905, Robert Warschauer & Co was taken over by the Darmstädter Bank, and Mendelssohn Bartholdy was able to live on the purchase price as a rentier. In 1907 he was ennobled on his own initiative and from then on bore the name Otto von Mendelssohn Bartholdy. His ennoblement was viewed critically by some relatives and considered unsuitable for a citizen from a respected bourgeois family.
In 1908 he became a member of the AGFA supervisory board, and from 1926 after the merger with Bayer and BASF he was on the supervisory board of I.G. Farben. Between 1919 and 1925 he also ran his own small private bank.
After the transfer of power to the National Socialists in January 1933, Otto von Mendelssohn Bartholdy stayed in Potsdam. He became the main shareholder of I.G. Farben. In 1938, by means of subsequent ordinances to the Nuremberg Race Laws, he was forced to resign from his supervisory board mandate. After the death of his wife Cecile, who was considered of mixed race, he had to move to the gardener’s house in his villa in 1943 and was threatened with deportation because he was considered a “Jew” himself. After he was arrested, he was released on the intervention of the Potsdam District President, Count von Bismarck-Schönhausen. He was arrested a year later in connection with the assassination attempt on Hitler on 20 July 1944. Otto von Mendelssohn Bartholdy survived the end of the Second World War in Potsdam.
After it became clear that he would not get back his possessions expropriated by the Nazis, but that they were subject to nationalization by the Soviet occupying power, he emigrated to Switzerland, where he died four years after the end of the war, on 26 July 1949 in Basel at age 81.
Link to Wikipedia biography (German)