Which composer created the twelve-tone technique and wrote Pierrot Lunaire?

Arnold Schoenberg created the twelve-tone technique and wrote Pierrot Lunaire.

Schoenberg developed the twelve-tone method in the early 1920s as a systematic approach to organizing the twelve notes of the chromatic scale. The method sought to avoid establishing one traditional tonal center by giving the pitch classes a structured order called a tone row.

Pierrot Lunaire, composed in 1912, predates Schoenberg’s mature twelve-tone method. It sets twenty-one poems by Albert Giraud in German translation by Otto Erich Hartleben and uses a distinctive ensemble of five players on instruments including piano, violin, cello, flute, and clarinet. Its vocal style is sprechstimme, between speech and song.

Schoenberg is sometimes grouped with his pupils Alban Berg and Anton Webern as the Second Viennese School. However, Schoenberg originated the twelve-tone system, while Berg and Webern developed their own responses to his ideas.