Flex Mentallo is a comic book character created by Grant Morrison for his run on Doom Patrol. Flex is in part a parody of Charles Atlas' long-running "The Insult that made a Man out of Mac" advertisements seen in American comics from the past.
In 1996, Flex Mentallo received his own four-issue mini-series written by Morrison and illustrated by Frank Quitely. The mini-series forms part of what Morrison calls a thematic hypersigil trilogy along with The Invisibles (which also featured artwork by Quitely, among many other artists) and The Filth.
Other articles related to "flex mentallo":
... Flex Mentallo received a cameo in the Batman The Brave and the Bold episode entitled "The Last Patrol!", which focuses on the Doom Patrol and contains a number of references and in-jokes ... and Niles Caulder attend a local carnival where Negative Man is working, and a large poster of Flex Mentallo is shown plastered on a wooden fence with the phrase "The Sensational Find ...