Billy Preston

Preston is seen on the Rhodes accompanying members of the Beatles during the "Let It Be" sessions.

Preston pioneered the use of the Clavinet during the recording of "Outa-Space" in 1972, according to this website.

"Preston, who died Tuesday at 59 in Los Angeles after a long, kidney-related illness that had left him in a coma since November, was a virtuoso on the Hammond B-3 organ. Two albums recorded before he was 20 were aptly titled 'The Wildest Organ in Town' and 'Most Exciting Organ Ever.'"