The Piano Sonata No. 8, Op. 66, by Alexander Scriabin, was composed between 1912 and 1913. As one of Scriabin's late piano sonatas, the eighth sonata is highly atonal, though arguably less dissonant than some of his other late works. Like Scriabin's other late piano sonatas, the eighth sonata reflects the composer's mystical interests. Scriabin saw some parts of this sonata, which, like the sixth sonata, he never performed in public, as "the most tragic episode of my creative work".
The eighth sonata consists of a single movement, and performances range from 10 minutes (Michael Ponti) to 15 minutes (Dmitri Alexeev).
This piece is regarded as one of Scriabin's most musically difficult pieces. It is more pages of music than any other of his piano works, and many parts of the piece are written on three and four staves, as opposed to the typical two staves, to accommodate the intertwined themes. The character of the eighth sonata is less pronounced than that of the Sixth and Seventh. There are fewer aggressive dissonances and no violent climaxes, and there are scarcely any explicative markings.
The eighth sonata begins in an almost uncomfortably serene manner. This languid episode deciduates quite quickly into an agitated, very chatty rhythm and melody. The piece moves along with quite some energy, as if it is pushed by a creative and inspired force. There are none of the characteristic instructions common in Scriabin's other late sonatas. The furthest he goes is the word "Tragique" to indicate moments in the music of an almost distressed apathy and futility. This sonata seems almost experimental, even by Scriabin's standards. It is extremely pastiche; some sections of the piece seem to be sewn together arbitrarily as in the section titled "presto" which begins with staccato chords bouncing away from the previous theme. There are moments of serenity, but a large portion of the music seems contagiously urgent and enthused with extreme energy. The composer Boris Asafiev argued that the themes in the piece represent natural elements 
Like his sixth sonata, Scriabin never performed this sonata in public. He considered parts of it "the most tragic episode of my creative work", and described its harmony as "drawn from nature, as if it had never existed before". Stravinsky described the piece as "incomparable."