(written from a Production point of view)
Richard Wagner was a 19th century German composer mentioned in a scene in the script of the Star Trek: The Next Generation episode "The Inner Light", though only by last name. The scene mentioning Wagner was not in the finished episode. .
Wagner was said to have composed the Ring cycle, which took nine hours to watch in one sitting. Wagner also composed the Bridal Chorus, which was heard in the Star Trek: The Original Series episode "Balance of Terror" and the Star Trek: Voyager episode "Course: Oblivion"; he also created the opera Tristan and Isolde, whose title appeared on a banner in VOY: "Future's End, Part II".