Wow! Can't believe that I missed this thread the first time around.

Lot of good choices. For whatever reason, I've always been partial to the jazz bassists. Maybe because they freely switch off between acoustic and electric, and often play more of the lead parts. Clarke, Pattitucci, and Pastorius have been mentioned.

Probably the most phenomenal bass player I've ever seen is Brian Bromberg. His speed and versatility are off-the-chart, and he plays just about every type of bass imaginable -- fretted, fretless, four-string, eight-string, five-string, acoustic, electric, piccolo bass, standup electric, etc.

Too bad he's not nearly as good a songwriter and puts out albums more in the blander smooth jazz vein. His albums feature some nice solos and the like, but it's nothing like the jaw dropping improvising and accompaniment that he does when unleashed in a live performance. He also does a lot of good session work, but there too he's limited by the material.

Another incredible bassist is Charlie Hunter. He's unusual in that he plays both the lead and bass guitar simultaneously using modified 10 and 12-string guitars. Aside from the incredible skill needed to pull this off, he's a great improviser. The interplay between the lead and bass parts in his songs is impressive, no surprise considering that he plays both parts.

Some reviewers have commented that Hunter could become a legend if he would just focus on one instrument -- that playing both parts impedes his potential to excel at one. But, I'm not so sure. His technique is so embedded into his songwriting and playing, but I just don't see him separating out the two parts, since his improvising hinges so heavily on working the lead guitar and bass parts together. He is capable of playing each instrument by themselves, but I'm not sure that he would be better off focusing on one.