Greg Rzab (born 1959, Chicago) is an American musician, a bass guitar player.
Greg played for several years with Otis Rush's band, with Buddy Guy's band (1986-1998), and he also had a number of stints, tours, sessions, and records with other famous blues performers. In 2000, he was a member of the touring lineup of The Black Crowes and is featured on the bonus tracks of their 2000 album Live at the Greek with Jimmy Page.
Since 2009 he is a member of a new lineup of the Bluesbreakers.