Philippe-Antoine Merlin, known as Merlin de Douai (30 October 1754 – 26 December 1838) was a French politician and lawyer.
Merlin de Douai was born at Arleux, Nord, and was called to the Flemish bar association in 1775. He collaborated in the Répertoire de jurisprudence, the later editions of which appeared under Merlin's superintendence, and contributed to other important legal compilations. In 1782 he purchased a position as royal secretary at the chancellery of the Flanders parlement. His reputation spread to Paris and he was consulted by leading magistrates. The Duke of Orléans selected him to be a member of his privy council.
In Elected to the States-General for the Third Estate in Douai, he was one of the chief of those who applied the principles of liberty and equality embodied in the National Constituent Assembly's Tennis Court Oath of 4 August 1789.
On behalf of the committee, appointed to deal with Ancien Régime nobility rights, Merlin de Douai presented to the Assembly reports on manorialism and the subjects of redistribution with compensation, and topics associated with that (hunting and fishing rights, forestry, etc.). He carried legislation for the abolition of primogeniture, secured equality of inheritance between relatives of the same degree, and between men and women. He also prepared the report for the Assembly which argued that no compensation should be paid to the German princes whose lands in Alsace were forfeit when France incorporated them.