Carl Ferdinand Allen (April 23, 1811 – December 27, 1871) was a Danish historian and professor.
He spent three years (1845-1848) researching at the archives of England, France, the Netherlands, Italy and Germany; upon completion of this task, he returned to Denmark.
In 1851 he became a lecturer at the University of Copenhagen and, in 1862, a professor of history and northern archaeology.
He wrote the work following years of examinations of the archives of European nations.
In Om Sprog og Folke-Eiendommelighed i Hertugdømmet Slesvig eller Sønderjylland ("About Language and Singularity in the Duchy of Schleswig or Sonderjylland"), Allen depicted the Germans in a negative way and accused them of having intrinsic urge to expand and to dominate other peoples.