Antoine Claude Nicolas Valdec de Lessart (25 January 1741, Château de Mongenan, Portets, near Bordeaux – 9 September 1792, Versailles ) was a French politician. He was the illegitimate son of the Baron de Gasq, Président of the Parlement de Guyenne.
A director of the Compagnie des Indes, he became Maître des requêtes in 1767 then in October 1788 one of the three commissaries charged with discussing and examining everything on the financial administration. Claude Antoine Valdec de Lessart was one of the intimates of Jacques Necker. Louis XVI of France made him one of the commissaries charged with reconciling the three orders of the Estates General.
On 4 December 1790, he was summoned to the Contrôle général des finances, then on 25 January 1791 moved to the Interior Minister, all the while holding onto the finance portfolio. At the Financial ministry, Étienne Clavière and the Girondins preyed on his management of the post, whilst at the interior ministry Camille Desmoulins, Louis-Marie Stanislas Fréron and Jean-Paul Marat reproached his sympathies for the refractory clergy. During the Varennes affair, he revealed himself as a docile executor of the orders of the Legislative Assembly. He was then made interim Naval Minister in September 1791 and interim minister of foreign affairs that October.