Laurent-Théodore Biett (25 July 1781 – 3 March 1840) was a Swiss-born dermatologist from Schams in the canton of Graubünden.
He is chiefly remembered for introducing into France an anatomical methodology of analyzing skin diseases; a system that was first developed by the British dermatologist Robert Willan (1757–1812).
He received his initial medical education at the Hôtel-Dieu de Clermont-Ferrand [fr], relocating to Paris in 1801, where he became a favourite student of Jean-Louis Alibert.
When Alibert's work at the Hôpital Saint-Louis was interrupted by royal obligations, Biett filled in for his teacher.
Biett was not known for his published works, however two of his students, Pierre Louis Alphée Cazenave and Henri Édouard Schedel, took assiduous notes of his lectures.