D'Artagnan was a real, noted French soldier in the 17th century, publicly best known for his appearance as one of the main characters in The Three Musketeers and following books by Alexandre Dumas, père.
When Hikaru Sulu under the influence of polywater intoxication, had attacked the bridge crew believing Captain Kirk to be Richelieu and been rendered unconscious in 2266, Spock ordered crewmen to take "D'Artagnan here" to sickbay. (TOS: "The Naked Time")