String Quartet No. 12

The String Quartet No. 12 in E♭ major, Op. 127, by Ludwig van Beethoven, was completed in 1825. It is the first of Beethoven's late quartets.

The work is composed of four movements and a typical performance of the work takes around 36–38 minutes. Beethoven initially planned two additional movements: one between the first and second, and another between the third and fourth.

In the first edition of 1826, published by Schott, the finale had no initial tempo marking (other than Finale) (and the third movement's opening indication was "Scherzo: Vivace", not "Scherzando vivace").

The first movement is twice interrupted – just before the development of the sonata form begins, and when that section is almost but not quite over – by recurrences of the opening's maestoso music.

The immense second movement is in the subdominant key of A♭ major. It consists of a set of six variations and a coda.

The penultimate variation recapitulates the theme after a contrasting section in the submediant, while the final variation restores the tonic and basic thematic material after an episode in the subdominant. Beethoven based this tonal progression on the finale of the Ninth Symphony (Op. 125) where the orchestral double fugue episode in B♭ is followed by the "grand" variation for full orchestra and choir in D major, followed by the "Seid umschlungen" episode in G major, which moves into the choral double fugue in the tonic D major.

The scherzo's trio is a Presto of a kind Beethoven did not use very often, though it is similar in sound and phrasing to some of his bagatelles from the contemporary Op. 126 set.