August Friedrich Kellner (February 1, 1885 – November 4, 1970) was a mid-level official in Germany who worked as a justice inspector in Mainz and Laubach. During the First World War, Kellner was an infantryman in a Hessian regiment. After the war he became a political organizer for the Social Democratic Party of Germany, which was the leading political party during the time of the turbulent and short-lived Weimar Republic, Germany’s first period of democracy. Kellner campaigned against Adolf Hitler and the Nazis. During World War II, working as a civil servant at a small court house, he wrote a diary to record his observations of the Nazi regime. Based on conversations and attentive reading of newspapers, he described the various crimes of that regime. He titled his work Mein Widerstand, meaning "My Opposition". After the war Kellner served on denazification boards, and he also helped to reestablish the Social Democratic Party. He gave his diary to his American grandson in 1968 to translate into English and to bring it to the attention of the public. In the epilogue, the author's grandson Robert Scott Kellner tells how the diary came to be published in German:- German publishers were not interested until in 2005 it was reported in Der Spiegel that former US President George H. W. Bush had looked at Kellner's original notebooks in the George Bush Presidential Library at Texas A&M University. He explained his purpose for writing the diary:
- "I could not fight the Nazis in the present, as they had the power to still my voice, so I decided to fight them in the future. I would give the coming generations a weapon against any resurgence of such evil. My eyewitness account would record the barbarous acts, and also show the way to stop them."
The diary was published in 2011.