Paris Métro Line 12 is one of the sixteen lines of the Paris Métro. It links Issy-les-Moulineaux, a suburban town southwest of Paris, to Aubervilliers, in the north. With around 54 million passengers per year, Line 12 was the twelfth busiest line of the network in 2021. It has several major stops, such as Madeleine, Concorde, Porte de Versailles and two national railway stations, Gare Montparnasse and Gare Saint-Lazare. The service runs every day of the week, and the line uses MF 67 series trains, the network's standard since the early 1970s.

The Paris Métro, operated by the Régie autonome des transports parisiens (RATP), is a rapid transit system in the Paris metropolitan area, France. A symbol of the city, it is known for its density within the capital's territorial limits, uniform architecture and unique historical entrances influenced by Art Nouveau. The system is 226.9 kilometres (141.0 mi) long, mostly underground. It has 308 stations of which 64 have transfers between lines. There are 16 lines, numbered 1 to 14, with two lines, Line 3bis and Line 7bis, named because they used to be part of Line 3 and Line 7, respectively. Line 1, Line 4 and Line 14 are automated. Lines are identified on maps by number and colour, with the direction of travel indicated by the terminus.