John Louis of Nassau-Hadamar, (Dillenburg, 6 August 1590 – Hadamar, 10 March 1653) and also known in German as Johann Ludwig, was a German nobleman and member of the House of Nassau who is best known for his role as an aide to the head of the imperial (Holy Roman Empire) delegation for the Peace of Westphalia, Count Maximilian von Trautmansdorff.

Highly indebted, John Louis was forced to sell Esterau to Peter Melander Graf von Holzappel in 1643.

John Louis was raised a Calvinist, as was sent in 1629 by his brothers as a diplomat to Vienna to negotiate a truce with Emperor Ferdinand II.

In 1645 he was added to the Imperial delegation under Maximilian von und zu Trauttmansdorff who negotiated the Peace of Westphalia.

Ferdinand III, Holy Roman Emperor made him a Prince (Fürst) and gave him a large sum of money.