Mentallo (Marvin Flumm) is a fictional supervillain, a mutant appearing in American comic books published by Marvel Comics. After having been fired for cause after attempting a covert S.H.I.E.L.D. takeover, he has since operated as both a freelance criminal and subversive and a high-ranking agent of HYDRA. He is usually depicted as using technology to increase his power.
Mentallo may refer to:
- Flex Mentallo - A DC Comics character
- Mentallo - A Marvel Comics character
- Mentallo and the Fixer - An American industrial music band
- Metallo, a similarly-spelled DC Comics character