Belsazar de la Motte Hacquet (also Balthasar or Balthazar Hacquet) (c. 1739 – 10 January 1815) was a Carniolan physician of French descent in the Enlightenment Era. He was a war surgeon, a surgeon in the mining town of Idrija, and a professor of anatomy and surgery in Laibach (now Ljubljana). He researched the geology and botany of Carniola, Istria, and nearby places, and was the first explorer of the Julian Alps. He also did ethnographical work among the South Slavic peoples, particularly among the Slovene-speaking population. He self-identified primarily as a chemist and introduced the methods of chemical analysis to Carniola.