There's really no way of ranking or highlighting the top famous 21st century pianists because there's so many genres - jazz, western classical, hip-hop, song-writing, pop, etc. So these 4 composers are in no order but have great achievements and are well-known and respected today as talented pianists.

Robert Glasper (Born 1978)

• Multi-grammy-winning pianist influenced from Jazz and Hip-Hop.
• American pianist, record producer, songwriter and musical arranger
• Genre: R&B/Soul
• Instruments: Piano, fender rhodes, keyboard

Lang Lang (Born 1982)

• One of the mouse famous classical musicians in the world with immense technical ability on the piano.
• Chinese pianist active in China, North America and Europe
• Genre: Western Classical
• Instrument: Piano

Cory Henry (Born 1987) 

• Multi-instrumentalist and was a former member of Grammy-winning group, Snarky Puppy.
• American singer-songwriter, pianist, organist and record producer
• Genre: R&B/Soul
• Instruments: Piano, organ, keyboards, vocals, harpejji, drums

Jacob Collier (Born 1994) 

• Multi-instrumentalist and became famous with his Grammy-winning arrangements of "Fascinating Rhythm" and "The Flinstones" theme on YouTube.
• English singer, songwriter and producer
• Genre: Combination of jazz and others
• Instruments: Vocals, keyboards, piano, double bass, bass guitar, drums, percussion, guitar, mandolin, ukulele ,harpejji, melodica