If it isn't cheating to go twice - Dave Pegg who is my bass-playing hero, adaptable to almost any musical context - folk of all stripes, jazz, rock, heavy rock, prog but always adding texture, harmony and interest - an absolute master of creating expression on the instrument.
Plus he single-handedly changed the role of the bass in folk and folk rock music for ever.
Look at this for an example of how his understated but melodic bassline delivers.