Theodor Creizenach (17 April 1818, Mainz – 6 December 1877, Frankfurt) was a German Jewish poet and historian of literature.
He studied classical antiquities in Giessen, Göttingen, and Heidelberg, and then lived for several years at Paris as tutor in the house of Aaron Anselm Rothschild.
Upon his return from Paris in 1842 Creizenach became teacher in the Jewish Philanthropin at Frankfort-on-the-Main, and was one of the principal founders of the Frankfort Jewish Reformverein; in 1854, however, he abandoned the faith of his fathers and embraced Christianity.
In conjunction with Oskar Jäger he took charge of the new edition of Friedrich Christoph Schlosser's Weltgeschichte, 1870 et seq.
; and in conjunction with Otto Müller edited a weekly publication, Das Frankfurter Museum.