Surprised nobody mentioned Al Jackson, Jr. of Booker T. the MG's and Sam and Dave, Otis Redding, Albert King, Rufus Thomas, Eddie Floyd, Johnnie Taylor and, basically, all the classic period STAX artists.
He continued his career by playing for all the early 70's Al Green hits on HI Records.
If you turn on an oldies station or a soul satellite channel, you'll hear Al Jackson, Jr. once every 25 minutes or so.