This name was common throughout the English-speaking world for most of the 20th century, though in the 1960s it began a slow decline in most places.
Famous bearers include the German intellectual Max Weber (1864-1920) and the German physicist Max Planck (1858-1947). This name is also borne by the title character in the Mad Max series of movies, starting 1979.
Apart from royalty, this name was only moderately popular in France during the Middle Ages. After the French Revolution, when Louis XVI was guillotined, it became less common.
The Normans brought the name to England, where it was usually spelled Lewis, though the spelling Louis has been more common in America. Famous bearers include French scientist Louis Pasteur (1822-1895), French actor Louis de Funès (1914-1983), Scottish author Robert Louis Stevenson (1850-1894), who wrote Treasure Island and Dr Jekyll and Mr Hyde, and American jazz musician Louis Armstrong (1901-1971).
In America, this name received a boost of popularity in 2000 when a character bearing it began appearing on the television series The West Wing.