Lancelot was a fictional character in an Earth fairy tale set in England. He was a great knight but also a womanizer.
Kira Nerys once knocked out Lancelot while in the holosuite with Jadzia Dax. She was unfamiliar with the storyline and became offended when he tried to kiss her, as she was playing a married woman at the time. Dax ended the program when this happened. (DS9: "The Way of the Warrior")