Co-written and first recorded by Eddie Floyd (US #28/R&B #1 1966).
Other hit versions by Otis Redding & Carla Thomas (US #30/R&B #8/UK #35 1967), David Bowie (1974 UK #10/IRE #4), Ami Stewart (US #1/UK #6/CAN #1/ 1979).
From the wiki: “Written by Eddie Floyd and Steve Cropper, ‘Knock on Wood’ was first recorded in 1966 by Eddie Floyd. According to Floyd, the line ‘It’s like thunder, lightning, the way you love me is frightening’ was inspired by a thunderstorm that was occurring the afternoon the song was written with Cropper, the famed Stax guitarist, in a Memphis hotel room.