The words marquee and marquis are sometimes confused. Though they have distinct meanings, interestingly enough, one of the terms begat the other.
Marquis stems from the Old French term marchis, meaning “border ruler,” from marche, meaning “frontier.” (The latter term was adopted into English as march.) Used in English since the Middle Ages, the title was incorporated into the hierarchy of noblemen: A marquis ranks just below a duke and above a count. In British English, the spelling marquess (with pronunciation consistent with the spelling) came to prevail over the French-influenced spelling and sounding. (The feminine form is marchioness.)
Marquee has nothing to do with the nobility—though it is sometimes used as an adjective referring to celebrity—but it once did. The dominant meaning, dating from the early twentieth century, pertains to a canopy or awning over the entrance to a theater or hotel (or to a large tent of the type used for outdoor events); by extension, it came to refer to a sign over theater or circus entrances labeled with the name of the production and the principal performers, or the name of the circus. When the age of electricity dawned, these signs came to be equipped with a perimeter of lightbulbs. (Later, these lights were sometimes rigged to turn on and off in a simple sequence or in a circuitous pattern; the latter effect is called chasing lights.)
So, what’s the connection? During medieval times, during military campaigns, knights and higher-ranking combatants used tents as temporary lodgings. Titled noblemen, including marquises, distinguished their tents from those of mere knights by adorning them with colorful canopies. This type of decoration, by association with the nobility, itself came to be called a marquise; because that term, borrowed into English, was misunderstood to be plural, it was corrupted to marquee when it was applied to refer to any similar adornment.
The term has also been applied, by association with the elegance of nobility, to a style of ring and a diamond cut, to a woman’s hat, to a piece of furniture, and even to a type of pear.