Frédéric Auguste Ferdinand Thomas de Reiffenberg (14 November 1795 — 18 April 1850) was a baron, Belgian writer, historian-medievalist, and linguist.

Accused of plagiarism, he was almost deprived of his chair, was dismissed from the examination board and left Liège.

He became one of the most active members of the Royal Academy of Science, Letters and Fine Arts of Belgium.

His son, Frédéric Guillaume de Reiffenberg, was a writer, poet, and playwright.

He wrote poems, drama plays, critical sketches, novels, articles, and books on military administration.