Louis Pierre Vieillot (May 10, 1748, Yvetot – August 24, 1830, Sotteville-lès-Rouen) was a French ornithologist.
Vieillot is the author of the first scientific descriptions and Linnaean names of a number of birds, including species he collected himself in the West Indies and North America and South American species discovered but not formally named by Felix de Azara and his translator Sonnini de Manoncourt.
At least 26 of the genera erected by Vieillot are still in use.
He was among the first ornithologists to study changes in plumage and one of the first to study live birds.