Otto Heinrich Frank

Otto Heinrich Frank was born into a German Jewish family. He was the second of four children born to Alice Betty (née Stern, 1865–1953) and Michael Frank (1851–1909). His elder brother was Robert Frank, and younger siblings were Herbert Frank and Helene (Leni) Frank. Otto was a cousin of the furniture designer Jean-Michel Frank and a grandson of Zacharias Frank. His father originally came from Landau, and moved to Frankfurt in 1879, marrying Alice Stern in 1886. Alice and Michael Frank placed value on a middle-class education. Otto had music lessons, learned to ride a horse and visited the theater and opera regularly. The Frank family enjoyed a large circle of friends, and kept a welcoming home. Otto studied economics in Heidelberg from 1908 to 1909 and had a work experience placement at Macy's Department Store in New York City thanks to a college friend his age, Nathan Straus Jr. However, after leaving for New York, he had to return home briefly because of his father's death in September 1909, before once again leaving for the United States. He returned to Germany two years later in 1911.

Frank worked in the bank that his father initially ran, which subsequently he and his brothers inherited until its collapse in the early 1930s. He married 25-year-old Edith Holländer – an heiress to a scrap-metal and industrial-supply business on 12 May 1925, at the synagogue in Aachen, Edith's hometown. Their elder daughter, Margot Frank (Margot Betti), was born 16 February 1926, followed by their younger daughter, Anne (Annelies Marie), on 12 June 1929. Edith died of starvation and disease in Auschwitz on 6 January 1945. In late October 1944, Margot and Anne were transferred from Auschwitz to the Bergen-Belsen concentration camp where they died of typhus.

In 1953, Frank married Elfriede (Fritzi) Markovits, a Holocaust survivor, who assisted him with the Anne Frank Foundation in Basel, which he launched a decade later. Markovits's daughter, Eva Schloss, was a Holocaust survivor, peace activist and international speaker.

In the years after the diaries were published, Otto Frank became embroiled in a series of legal battles with individuals who accused him or others of forging the manuscript; these cases would persist even after Frank's death in 1980. In 1959, Frank "lodged a criminal complaint on the grounds of libel, slander, defamation, maligning the memory of a deceased person and antisemitic utterances" against two members of the right-wing Deutsche Reichspartei, Lothar Stielau and Heinrich Buddeberg, who had dismissed the diary as a work of fiction.

In 1976, Nazi sympathizer Ernst Römer accused Frank of editing and fabricating parts of Anne's diary. Frank filed a lawsuit against him. As with the previous case, the court determined that the diary was authentic. Römer demanded a second investigation, but on this occasion the Hamburg District Court engaged the Bundeskriminalamt (BKA). It was claimed that parts of her diary were written with ballpoint pen ink, which did not exist prior to 1951. However, the BKA found that these parts were simply two scraps of paper not attached to the manuscript and clearly written in different handwriting. Some page numbers are presumed to have been added by Frank when compiling the diary for publication. No diary entry is written in ballpoint ink. Reporters were unable to question Frank, as he died around the time of the discovery.