Since his first introduction in Marvel Comics, Thanos has become a fan-favorite villain, so much so that he broke out from the page and onto the big screen as the Marvel Cinematic Universe’s main overarching antagonist. While Thanos ended up being a major hit, the creator of the Mad Titan seemingly didn’t see that coming, so much so that he didn’t think he’d be able to take his character and run with him within Marvel Comics continuity. Jim Starlin, the creator of Thanos, didn’t even think he’d have the chance to write a second comic book after jumping on the Iron Man series for a fill-in book, which is why that issue is stuffed full of Starlin’s original characters.
In Iron Man #55 by Jim Starlin and Mike Friedrich, Iron Man finds himself being attacked by strange alien life forms known as the Blood Brothers while also receiving telepathic messages from none other than Drax the Destroyer. Readers come to learn that the Blood Brothers were sent by Thanos to attack Iron Man in an effort to weaken the Avengers and make planet Earth easier to conquer. Drax, who was created by Kronos to kill Thanos, helps Iron Man escape the evil aliens’ clutches, then the two work together to stop the villainous Thanos.
In an interview published by Comic Book Resources, fans are given a deeper insight into why, with no build-up or preconceived planning, did Thanos, Drax, and even Thanos’ brother Eros all appear at once in a one-off Iron Man issue. “I felt that this may be my only chance to do a character, not having the confidence that my career was going to last anything longer than a few weeks. So they got jammed in.” Starlin explained. After working in comics for many years at that point, Starlin was given an opportunity by his Editor-in-Chief Roy Thomas to do a fill-in issue of Iron Man, and as Starlin mentioned, he didn’t think he’d last much longer in the comic book world, so the writer and artist took the opportunity and ran with it.
Jim Starlin used that Iron Man issue to introduce what would become some of the most popular characters in the current Marvel age. Drax the Destroyer is a favorite among MCU Guardians of the Galaxy fans, bringing with him humor as well as action that captivates even casual viewers. The legacy of Thanos speaks for itself as far as the impact he's had since his MCU debut, and even Eros hits the big screen after making an appearance at the end of the latest MCU film Eternals.
These one-off characters squeezed into a random Iron Man issue have since become big screen marvels, all of them breaking through the comic book threshold and into the films, reaching a whole new audience in the process. The fact that every character that made their debut in Iron Man #55 has been adapted to the films, including and especially Thanos, just speaks to the brilliance of Jim Starlin, a creative visionary that thought he wouldn’t even be allowed to write a second comic.
Source: CBR