Flottenrichter Otto Heinrich Kranzbühler (also spelled Kranzbuehler) (8 July 1907 – 9 August 2004) was a German naval judge who represented defendant Grand Admiral Karl Dönitz before the International Military Tribunal at the Nuremberg Trials.
Otto Kranzbühler was born in Berlin, German Empire, on 8 July 1907, the youngest son of German Lieutenant Commander Henry Kranzbühler (1871-1946). He had two sisters: Caroline (1898–1969) and Elizabeth (1904–1981) and one brother: Helmuth (1901–1978).
Kranzbühler graduated from secondary school in 1925. Following secondary school, Kranzbühler studied law in Freiburg, Bonn, Geneva, and Kiel, passing the German law exam by his 21st birthday in 1928. During his legal studies, Kranzbühler became particularly interested in boating – perhaps sparking his later interest in naval law.
In 1934, Kranzbühler voluntarily enlisted into the Reichsmarine. By 1937, he was sent to Berlin to act as a legal advisor to the Naval High Command. In 1943, he was sent to France and appointed as Naval Fleet Judge-Advocate, or Flottenrichter. Kranzbühler remained in France until the winter of 1944, when Germany withdrew from France. In the winter of 1944, Kranzbühler moved to Wilhelmshaven, the main operating base for the Kriegsmarine. By April 1945, Kranzbühler was arrested and detained for approximately four weeks by Allied Forces, along with other German navy judges.
During the immediate post-war period, both the British and the Americans utilized former Kriegsmarine personnel to maintain, transfer, and destroy Kriegsmarine vessels and assets, and to clear mines. Kranzbühler was not immune from these assignments, even though he was a Naval Judge. In fact, for several months, he served on the German Minesweeping Administration.
His minesweeping activities, however, were short lived. In October 1945, Kranzbühler was called by the agency of the British Royal Navy to Nuremberg to serve as defense counsel for Grand Admiral Karl Dönitz, Commander and Chief of the Kriegsmarine, before the International Military Trial in Nuremberg. Dönitz specifically requested Kranzbühler, a fellow Kriegsmarine, to represent him in his defense.