John Joseph Theodore Rzeznik (pronounced REZ-Nik), commonly known as John Rzeznik (born December 5, 1965 in Buffalo, New York), is the guitarist/vocalist of rock band the Goo Goo Dolls.

Prior to the album A Boy Named Goo, his bandmate, Robby Takac was the lead singer. During the era of the album Superstar Carwash, they collaborated on several songs. Although Rzeznik transitioned into becoming the lead vocalist, both men still share the duties of writing songs for the band’s albums, and Takac still sings lead vocals on several songs.