Carl Ludwig Siegfried Buchenau (born 30 November 1870 in Bremen; died 16 September 1932) was a German merchant, landlord and art collector in the early 20th century.
On 1 May 1913 Buchenau leased the manor house Niendorf along with the hunting grounds (Gut Weißenrode) from the city of Lübeck, where he resided until his death.
The couple's guests at Niendorf included the conductor and composer Hermann Hans Wetzler, who completed his Symphonic Fantasy for Orchestra, Op.
His daughter Margarete (born 1913) married the printer Alfred Zantop (born1900 in Wildungen), whom the Allies later suspected of being a Nazi agent in Spain.
Zantop is listed as a Red Flag Name in the Art Looting Investigation Unit Final Report of 1946.