Félix Joseph Henri de Lacaze-Duthiers (15 May 1821 – 21 July 1901) was a French biologist, anatomist and zoologist born in Montpezat in the department of Lot-et-Garonne. He was a leading authority in the field of malacology.
He studied medicine in Paris, and worked at Necker Hospital under Armand Trousseau (1801–1867). Later on, with Jules Haime (1824–1856), he travelled to the Balearic Islands to study marine life. In 1854 he returned to Paris as an assistant to Henri Milne-Edwards (1800–1885), and soon afterwards became a professor of zoology in Lille.
In 1865 he succeeded Achille Valenciennes (1794–1865) as chair of histoire naturelle des mollusques, des vers et des zoophytes at the Muséum national d'histoire naturelle, and in 1868 became a professor at the University of Paris. In 1871 he was elected to French Academy of Sciences in the department of anatomy and zoology.
Lacaze-Duthiers is remembered for his study of the anatomy and developmental history of mussels, coral, snails, brachiopods and other lower marine animals. In 1858 he discovered three mollusks in the Mediterranean that produced purple-blue dyes. One of the species, named murex trunculus, was the source of the distinctive purple-blue dye used by the ancient Phoenicians and Canaanites.