Louis of France was a notable King of France on Earth.
In 2269, Montgomery Scott sarcastically suggested he would follow Abraham Lincoln, along with Robert the Bruce, before the former US President was apparently beamed aboard the USS Enterprise. James T. Kirk assured him that if either other man came aboard, they would be given the honors due them as well. (TOS: "The Savage Curtain")
It is unclear which Louis Scotty meant, as there have been a number of kings with that name. The 9th ("Saint-Louis"), 14th ("Sun King") and the 16th (guillotined after the French Revolution) may be the most well known outside of France.
Louis XIV' name appeared in an unseen portion of the Picard family album created for Star Trek Generations, on an original charter sent from his court dated to 1662.