Josh Brolin Reveals A Shocking Fact About Thanos In The MCU

Even as the Marvel Cinematic Universe plunges through Phase 4 (and into the multiverse of it all), Josh Brolin's performance as Thanos remains the gold standard for the franchise's villains. Thanos served as the overarching villain for all of the first three phases of the MCU, finally taking the stage in  2018's "Avengers: Infinity War" — where he defeats all of the Marvel superheroes in one fell swoop — followed by his subsequent death the following year in "Avengers: Endgame."

Other Marvel villains have come to be iconic, but none have had the same impact as Thanos, particularly not across multiple films. The closest parallel is Loki, but even the God of Mischief develops into more of an antihero than a villain by the time Thanos murders him in "Infinity War," a trend that has only continued with his variant in the Disney+ series "Loki." Other villains who have a comparable impact on the audience, like Erik Killmonger (Michael B. Jordan) have rarely lasted past a single film.

In a recent interview on the Jess Cagle Show on SiriusXM, Brolin said that he would likely return as Thanos if Marvel Studios ever asked him to (via YouTube). That seems unlikely. The Avengers have now killed two separate versions of Thanos, and more multiverse trickery required to bring the character back may only dampen the emotional weight to his story arc across the most recent "Avengers" films. However, in the same interview, Brolin made some surprising remarks about how Marvel's mightiest villain developed, behind the scenes, from his original appearance until "Infinity War."

Josh Brolin said that Thanos' position as Infinity Saga's key villain wasn't always the definite plan

In the same SiriusXM interview, Brolin acknowledged that Thanos was not necessarily intended to be the MCU's major overarching villain back when audiences got their first glimpses of the Mad Titan in 2012's "The Avengers."

"The whole Thanos character, it was [originally] more of a cameo, but they liked the character so much," Brolin said (via the SiriusXM YouTube). "[Marvel Studios] had never felt like they had a villain that was substantial enough for what they were creating and then I think they felt like they found it, and then there were two movies that kind of revolved around it. It was a lot of fun and it worked out for them very nicely."

Brolin is right about this: Thanos' first appearance in the post-credits scene to "The Avengers" merely teases the character's existence in the MCU. Thanos doesn't even speak in that scene — it's not until "Guardians of the Galaxy" that Brolin starts voicing the character in what remains a small role for the film. Thanos' development within the MCU seemed a fluid process over the years, in fact. While his introduction clearly set the stage for a bigger role down the line, Joe and Anthony Russo have explained in the years since that while Marvel Studios does have a loose guideline of where they want the big story to go, the finer details — such as which characters will play a big role — get swapped out all the time (per Deadline).