While many Marvel and DC Comics heroes and villains have been parodied throughout The Boys, the comic’s version of Infinity War revealed why there was never a satirical take on Thanos. In The Boys #22 from Dynamite Comics, it’s revealed that a deadly incident forced numerous in-universe comics to be scrapped and rewritten, so the word “war” was removed, ultimately changing The Seven’s Infinity “War” into “The Infinity Debate.” That meant no big bad villain to avoid scaring the general public.
In The Boys comic book series, the incident that changed The Seven forever occurred in the story’s version of 9/11. In The Boys #21, the superteam attempt to save a hijacked plane, only for Homelander to lose control and start killing innocent people they were trying to protect. Ultimately, Homelander’s actions would lead to the death of not only his fellow Supe, Mister Marathon, but led to the plane crashing into the Golden Gate bridge, killing thousands of people. With the incident, the in-universe comics that gave the public fake stories that made them idolize the real-life Supes drastically changed their stories, which explains why there was no “Infinity War” or version of the villain Thanos in the series.
In The Boys #22 by Garth Ennis, Darick Robertson, Simon Bowland, and Tony Avina, Hugie learns about the history of The Seven from The Legend, the man who penned the in-universe comic book stores that essentially served as propaganda for Supes. He reveals that after the plane crash, The Seven were forced to stay out of the public eye, as Victory Comics, the universe’s version of Marvel Comics, stopped all their comics from publishing while scrapping, rewriting, and changing stories to avoid mentioning the word “war.” It was a concerted effort to avoid portraying the heroes in a violent light. As a result, their version of the Thanos-starring Infinity Saga became “The Infinity Debate,” as The Seven never had their own overarching villain.
Considering the Infinity Saga in The Boys universe became the Infinity Debate, it explains why they never had a parody version of the villain Thanos. Victory Comics didn’t want to draw attention to the deadly incident with The Seven, so in-universe comics were changed to reflect that – potentially canceling out any Thanos-level thread they’d face in the stories.
With all that said, that doesn’t mean that a version of Thanos isn’t out there somewhere in The Boys universe. But, in the in-universe comics showing the most incredible (and made-up) feats of The Seven, the Infinity Debate took a much lighter approach than the Infinity War comics from Marvel as they wanted to portray the Supes in a non-deadly manner, which meant no parody of the villain Thanos.