Gregory Walter Graffin, Ph.D. (born November 6, 1964) is an American punk rock musician, college professor, and author. He is most recognized as the lead vocalist and songwriter of the noted Los Angeles band Bad Religion, which he co-founded in 1979 and is the band's only constant member, even though it now features two other original members, guitarist Brett Gurewitz (who left and rejoined the band twice) and bassist Jay Bentley (who left in 1982, but returned in 1986). He also embarked on a solo career in 1997, where he released the album American Lesion. His follow-up album, Cold as the Clay was released nine years later. Graffin obtained his Ph.D. at Cornell University and has lectured courses in life sciences and paleontology at the University of California, Los Angeles.

Gregory Walter Graffin (meist nur kurz Greg Graffin; * 6. November 1964 in Racine, Wisconsin) ist ein amerikanischer Sänger, Songwriter sowie Hochschullehrer.

Gregory Walter Graffin (né le à Racine dans le Wisconsin, États-Unis), plus connu sous le nom de Greg Graffin est le chanteur et un des fondateurs du groupe de punk rock Bad Religion. Il est également un universitaire spécialiste de la théorie de l'évolution.

Gregory Walter "Greg" Graffin, född 6 november 1964 i Madison, Wisconsin, är en amerikansk musiker, sångare i punkrockbandet Bad Religion och forskare (filosofie doktor).

Greg Graffin, właściwie Gregory Walter Graffin (ur. 6 listopada 1964 w Racine, Wisconsin) –  wokalista i jeden z założycieli zespołu punkowego Bad Religion.