u’ ([ʔuʔ], beginning and ending with a glottal stop) is the first opera in the Klingon language, billed as “The first authentic Klingon opera on Earth”. It was composed by Eef van Breen to a libretto by Kees Ligtelijn and Marc Okrand under the artistic direction of Floris Schönfeld. The story of ’u’ is based on the epic legend of “Kahless the Unforgettable”, a messianic figure in the fictional Klingon history.

The premiere of the opera in The Hague on 10 September 2010 was a success, and the opera has been revived since then.