I'll only mention a few that have influenced me personally and whose work has passed the test of time. So, I'm eclectic...

Josh White
Chet Atkins
Merle Travis
Jerry Reed
Django Reinhardt
Charlie Byrd
Andres Segovia
Red Shea
Gordon Lightfoot
Laurindo Almeida
Sabicas
Carlos Mentoya
Bud Dashiell
Travis Edmonson
Paul Prestopino
Wes Montgomery
Leadbelly