The Best Piano Works of the 20th Century

My nonimations are:

Vignt Regards sur L’Enfant Jesus by Olivier Messiaen, and

The People United Will Never be Defeated by Frederic Rzewski

How about you?
9e7ba07d 49a7 4363 a6bc 1ea80b28ce42phomchick
Trilogy, Karn Evil 9-2nd Impression - Keith Emerson
Gymnopedie - Eric Satie
Ecologue for Piano and Strings - Gerald Finzi
I was going to nominate Modest Mussorgsky’s "Pictures At An Exhibition", but during a little research learned that though the work became very popular and often performed after orchestrations were written for it in the early 1900’s, most famously by Maurice Ravel in 1922, Mussorgsky’s original piano transcription was written in 1874, and published in 1886, five years after the composer’s death. I love the work, both as performed on solo piano, and with full orchestration.
The works of Conlon Nancarro for player piano! I have a multi - CD set of these!
Epic piano concertos of the 20th century in my book:

  • Rach-3
  • Rach- Rhapsody on a theme by Paganini
  • Prokofiev-3Ravel- Concerto in G major
  • Poulenc—concerto for two pianos
  • Bartok- 2 (for modernist listeners)                                     and why not,
  • Messiaen: Vingt regards
I don't know about being the greatest anything, but Stravinsky wrote some good stuff for solo piano.  I really like this record and recommend it to anyone who is remotely interested in solo piano stuff.

Anyone up for Kaikhosru Sorabji’s "Opus Clavicembalisticum"? It is about 4.5 hours long and almost every minute is exhausting to listen to because of the complexity and changing rhythm. I particularly like the last two sections of the work (the fugue and the coda section).

I also agree that the Nancarro works are amazing. They are not conventional piano works and cannot possibly be played by a human.

Ravel's - Gaspard de la nuit and Debussy' Preludes. Both are post 1900 as are most of these composers music for solo piano. Their music should not be missed. 
I love "Gaspard" and the Debussy Preludes.  I think Satie is also worth looking into, although his most popular works were composed in the late 19th century.
Gershwin's "Rhapsody in Blue", a uniquely American piece always has to be included in 20th century piano music. I agree with all of gregm's choices less  the Massiaen piece but will sure check it out! The impressionistic work Clair de lune by Debussy  would be on my list as well, less clear is when it was penned.
I was looking for pieces for solo piano, but I wasn’t clear. Regardless, there are some great suggestions here. Nancarrow is an excellent suggestion. I’ll add Prokofiev’s Piano Sonatas. 
I overlooked Prokofiev’s. :-(  FWIW I highly prize Chiu’s 9 CD traversal of all of his music for solo piano including some transcriptions. I also overlooked Rachmaninoff’s 24 Preludes and Sonata #2.
+1 on the Chiu suggestion

my additions would be the Shostakovich piano sonatas and something else I’m really into which reminds me of the Rzewski is Maxwell Davies’ “Farewell to Stromness” from The Yellowcake Review
I'm partial to early 20th century 'modern' piano-e.g., Scriabin.
Spare, angular, but not atonal. 
 But the one of the best artists who 'covered' him was his son-in-law and the recordings--from Russia- are not great. 
Should we add particular interpretation we like? There are some recordings of a certain work that give an overall better impression. I am not talking about "audiophile" standards, but about the music itself. of course, it will depend on a personal taste, but it may be worth a try.

Having said that, all my favorites are from way before 20th century, save for Satie, so I cannot even participate. I will peruse this thread to explore, though. Thanks everybody.
As far as "improvised" 20th century music is concerned, two of the most fertile minds and virtuoso pianists were Art Tatum ( "I got rhythm" 1940 from the "California melodies" radio program) and Bud Powell ( "Tempus Fugit" 1949 Clef records)  I love Scriabin and Nancarrow,but when it comes to emotionally charged,thrilling,fly by the seat of your pants piano I bow down to these two recordings. And yeah,Jazz WAS the greatest music of the 20th century....Was, I emphasize.
If you're interested in something relatively current,and noted as "Gourmet Jazz",  I will highly recommend Bill Laurance : " After Sun,"" Swift", or "Flint "( "Ready Wednesday" - My personal fav ).  I originally downloaded Flint from HD Tracks, then "Live at Union Chapel" and "After Sun" recently, but "Swift" was from his website.  All are exceptionally well recorded and addictive.

Happy listening...  
Bartok sonata, Alban Berg Sonata.
I always loved Rachmaninoff: Piano Concerto No.2
I always loved Rachmaninoff: Piano Concerto No.2
1901. You got in under the wire. 

Marta Argerich playing anything, or the Richter recording of Shostakovich Piano Concerto #1. 
+1 for Martha Argerich playing anything!!!