Mentzer is a surname. Notable people with the surname include:
Ethan Mentzer, member of the Click FiveFrank Mentzer, American fantasy authorJohn Thomas Mentzer, University of Tennessee marketing and logistics professorMike Mentzer, American IFBB professional bodybuilderRay Mentzer, bodybuilder and brother of Mike MentzerSteven Mentzer, Republican member of the Pennsylvania House of RepresentativesSusanne Mentzer, operatic mezzo-sopranoWilliam C. Mentzer, aeronautical engineer