Great subject!
Dave Edmunds, the fantastic Welsh guitarist, singer, and producer (The Everly Brothers, The Fabulous Thunderbirds, The Stray Cats, his and Nick Lowe’s Group Rockpile, many others). His first two albums Rockpile (album title, not the Group) and Subtle As A Flying Mallet are mostly all he playing and singing every note. My favorite living musician.
Emitt Rhodes, whose self-titled debut album is he alone playing every instrument and singing every note of the all self-written songs. Better than the released-around-the-same-time debut solo album by my next nominee.
Paul McCartney, obvious but still worthy.