The Marais is a historic district in Paris, France. It spreads across parts of the 3rd and 4th arrondissements on the Rive Droite, or Right Bank, of the Seine. Having once been an aristocratic district, it is home to many buildings of historic and architectural importance. It lost its status as a fashionable district in the late 18th century, with only minor nobles calling the area home. After the French Revolution, the district fell into disrepair and was abandoned by nobility. After a long period of decay, the district has undergone transformation in recent years and is now once again amongst the more fashionable areas of Paris, known for its art galleries, upscale restaurants and museums.

The 3rd arrondissement of Paris is one of the 20 arrondissements (districts) of the capital city of France. In spoken French, this arrondissement is colloquially referred to as "le troisième" meaning "the third". Its postal code is 75003. It is governed locally together with the 1st, 2nd and 4th arrondissements, with which it forms the 1st sector of Paris, Paris Centre.