String Quartet No. 14 in C-sharp minor, Op. 131 is a chamber music composition by Ludwig van Beethoven, completed in 1826. It is one of his late quartets and is known for its innovative structure, consisting of seven interconnected movements that flow seamlessly into one another. The quartet is celebrated for its emotional depth and complexity, showcasing Beethoven's mastery of form and harmony. It explores a wide range of moods, from introspective and serene to intense and dramatic, making it a significant work in the classical music repertoire.