The Symphony No. 9 in D minor, Op. 125, is a choral symphony, the final complete symphony by Ludwig van Beethoven, composed between 1822 and 1824. It was first performed in Vienna on 7 May 1824. The symphony is regarded by many critics and musicologists as a masterpiece of Western classical music and one of the supreme achievements in the history of music. One of the best-known works in common practice music, it stands as one of the most frequently performed symphonies in the world.

A choral symphony is a musical composition for orchestra, choir, and sometimes solo vocalists that, in its internal workings and overall musical architecture, adheres broadly to symphonic musical form. The term "choral symphony" in this context was coined by Hector Berlioz when he described his Roméo et Juliette as such in his five-paragraph introduction to that work. The direct antecedent for the choral symphony is Ludwig van Beethoven's Ninth Symphony. Beethoven's Ninth incorporates part of the ode An die Freude, a poem by Friedrich Schiller, with text sung by soloists and chorus in the last movement. It is the first example of a major composer's use of the human voice on the same level as instruments in a symphony.