Karl Ludwig August Friedrich Maximilian Alfred, Freiherr von Prel, or, in French, Carl Ludwig August Friedrich Maximilian Alfred, Baron du Prel, was a German philosopher and writer on mysticism and the occult. In the literature it has become customary to refer to him under various abbreviated French forms of his name, usually "Carl Du Prel," "Baron Carl Du Prel," or simply "Baron Du Prel."