I don't think they would be considered unknown except the fact that jazz seems not to be a mainstream music genre, but my uncle has introduced me to quite a few artists.

Stanley Clarke

Pat Metheny

Jaco Pastorius

I think you would probably know those. Plenty of good stuff from them. The others that stood out to me were:

Gabor Szabo

Al Di Meola

I tend to enjoy instrumental stuff in all genres and had not listened to much jazz before so it's great to have a plethora of "new" music to explore.