René Louiche Desfontaines (February 14, 1750 – November 16, 1833) was a French botanist.

Desfontaines was born near Tremblay in Brittany. He attended the Collège de Rennes and in 1773 went to Paris to study medicine. His interest in botany originated from lectures at the Jardin des Plantes given by Louis Guillaume Lemonnier. He excelled in his new interest and was elected to the French Academy of Sciences in 1783.

Desfontaines spent two years in Tunisia and Algeria, returning with a large collection of plants. He wrote Flora Atlantica (1798–1799, 2 vols), which included 300 genera new to science. In 1786 he was appointed professor of botany at the Jardin des Plantes, replacing Lemonnier. He later became director of the Muséum National d'Histoire Naturelle, was one of the founders of the Institut de France, president of the Academy of Sciences, and elected to the Légion d’honneur.