"Spider" John Koerner is an American guitarist, singer, and songwriter. He is best known as a guitarist and vocalist in the blues trio Koerner, Ray & Glover, with Dave Ray and Tony Glover. He has also made albums as a solo performer and with Willie Murphy.

Koerner, Ray & Glover was a loose-knit group of three blues musicians from Minneapolis, Minnesota: "Spider" John Koerner on guitar and vocals, Dave "Snaker" Ray on guitar and vocals, and Tony "Little Sun" Glover on harmonica. They were notable figures of the revival of folk music and blues in the 1960s.