Approximately 13% of the population are left handed and therefore musical instrument manufacturers provide only a small selection of left handed models. Bass guitars are no exception and a left handed bass guitar is a virtual mirror image of a right handed model with everything swapped to the opposite side of the instrument.
Probably the most famous left handed bassist is none other than Paul McCartney who custom ordered a left handed model of the Hofner Violin bass during The Beatles period of frequenting Hamburg in Germany in their formative years. His fame and celebrity status caused the left handed Hofner Violin bass to become an icon in rock history and is synonymous with the Beatles and McCartney himself.
For those of you choosing a left handed bass guitar you'll need to search diligently. There are many left handed models out there and most of them are very good, but for every 10 right hand models made there's only one left handed version. It gets slightly easier as you move up to the higher end of the market; many manufacturers that make custom guitars to order will happily create left handed models at no extra cost, although customers should be aware this is essentially only for the more expensive models of bass guitar.