Herbie Hancock

Herbie Hancock played on Joni's Mingus album, and in 2007 released River: The Joni Letters, an album of Joni covers. There are three songs on there from Blue: A Case Of You, All I Want and River (sung by Corinne Bailey Rae):

To me these versions are pretty much sacrilegious but Joni obviously disagrees - here she is singing River with Herbie:

So here's a link to Herbie's album on Spotify.