Hofner 500/1

The  Höfner 500/1 violin bass (nicknamed the  "Beatle bass" or  "Cavern bass") is a  hollow-bodied  bass guitar manufactured by  Höfner under several varieties. It was introduced in the mid-1950s and gained celebrity during the 1960s as one of the primary basses used by  Paul McCartney of  The Beatles.

Trivia

 * If not for the cheap price of the Hofner Bass, Paul's first choice would've been a Fender Jazz Bass.
 * This guitar (along with the Rickenbacker 325 and Gretsch Duo Jet) were made into guitar peripherals for The Beatles Rock Band.