Marc-Antoine Parseval des Chênes (27 April 1755 – 16 August 1836) was a French mathematician, most famous for what is now known as Parseval's theorem, which showed that the Fourier transform is unitary.
He was born in Rosières-aux-Salines, France, into an aristocratic French family, and married Ursule Guerillot in 1795, but divorced her soon after.
A monarchist opposed to the French Revolution, imprisoned in 1792, Parseval later fled the country for publishing poetry critical of the government of Napoleon.
His only mathematical publications were apparently five papers, published in 1806 as Mémoires présentés à l'Institut des Sciences, Lettres et Arts, par divers savants, et lus dans ses assemblées.
This combined the following earlier monographs: It was in the second 1799, memoir in which he stated, but did not prove (claiming it to be self-evident), the theorem that now bears his name.