Which composer wrote music that juxtaposed unrelated harmony and chromatic progressions

This is a
complex issue, and the answer depends on how broadly, or conversely how specifically, we define
the juxtaposition of unrelated harmony and chromaticism. We'll use the broader approach and
identify instances that fit this description in many different ways.

Throughout what is known as the common practice period (from 1700 to 1900), when
composers wrote in a "tonal-harmonic" style (meaning their music was
tonal, that is, written in a particular key), at intermittent points they
would use jarring harmonic progressions and extreme chromaticism for emotional effect and to
support the meaning of the text in religious music or in opera and song. Just a few examples of
many from the Baroque and Classical periods:

Bach. In the
"Crucifixus" section of the Mass in B minor.

Mozart. In the climactic scene of Don Giovanni.

Haydn. In the opening section of The Creation.

Beethoven. To some extent in all of his symphonies, especially in the development
section of the first movement of No. 3 (the Eroica), and in No.
9.

The above are a mere handful of examples. In the Romantic period
(1825-1900) chromaticism and unusual harmonic shifts came to be used even more frequently. We
can continue to point out individual instances. In the second movement of Schubert's late B-flat
Piano Sonata (D.960) there is a sudden progression to a distant key so striking it has sometimes
been termed the "magic modulation." As the nineteenth century progressed, however, the
two composers whose music most showed continuous chromaticism and harmonic progressions in which
the basic sense of being in one tonality (key) was lost were Liszt and Wagner. See, especially,
Wagner's opera Tristan and Isolde, and Liszt's B-minor Sonata and late
piano works. These prefigured various techniques that became common in the modernist period,
beginning around 1910.

In modernist, or avant-garde, twentieth-century music,
composers no longer wrote tonally (in the tonal-harmonic style of the
common-practice period). Thus music was no longer in a single tonality or key, but could combine
or superimpose multiple keys upon each other, as Charles Ives (see his The Unanswered
Question ) and Igor Stravinsky (see his Petrushka and
The Rite of Spring) did. This is called bitonality or polytonality. Even
more radical was Arnold Sch¶nberg, who developed a system called
dodecaphony--also called twelve-tone music, serialism, or atonality--in
which all notes of the chromatic scale are equal. Here the music is heavily and continuously
chromatic, and is not written in any key.