Louis XVII (Louis Charles), 1785–1795?, titular king of France (1793–95), known in popular legend as the "lost dauphin." The second son of King Louis XVI and Queen Marie Antoinette, he became dauphin at the death (1789) of his elder brother. In 1792 the revolutionists imprisoned him with the royal family in the Temple. After the execution (1793) of Louis XVI, the comte de Provence (later King Louis XVIII) proclaimed the dauphin king as Louis XVII, but he remained in prison until his death. Cruel treatment by his jailer, Antoine Simon, was said to have hastened his end.
His death has often been disputed; it was rumored that someone had taken the true dauphin from prison and substituted another boy in his place. Evidence, however, has long indicated that the boy really died in prison in 1795, and historians, for the most part, have disregarded the lost dauphin theory altogether. In 2000 geneticists announced that they had compared DNA from the dead boy's preserved heart with DNA from members of the royal family and proved conclusively that the child who died in prison was indeed the dauphin.
For the life of Louis XVII and discussion of the claims of various pretenders see study by H. G. Francq (tr. 1971).