X is the tenth album by Klaus Schulze. It was originally released in 1978, and on X Schulze attempted to execute a concept album of six "musical biographies" evoking contemporary or historical intellectuals with an influence on Schulze: Friedrich Nietzsche, Georg Trakl, Frank Herbert, Friedemann Bach, Ludwig II. von Bayern, and Heinrich von Kleist. The work is from the classic era of Berlin School.