Otto Freiherr von Brandenstein (21 October 1865 – 8 May 1945) was a German officer.
He joined the Prussian Army in 1885 and was promoted to oberstleutnant in 1913.
During the World War I, Brandenstein served in the Western Front as a staff officer under the command of the generals Gustav Freiherr von Hollen and Eberhard von Claer.In 1918, colonel Brandenstein was the commander of the formed cavalry brigade Detachment Brandenstein which landed in Loviisa, Finland in 3 April.
The brigade joined the Finnish Civil War and fought with the Finnish Whites.