WARNING: The following article contains major spoilers for Avengers: Infinity War, in theaters now.
With a few exceptions, Marvel Studios has managed to pack Avengers: Infinity War with almost every hero who has appeared in the Marvel Cinematic Universe. Fans. One thing the ensemble film 10 years in the making also accomplished is tossing in a surprise cameo from a character that hasn't been seen since the Phase One slate of movies.
Five of the Infinity Stones have debuted in the MCU prior to Infinity War -- Space Stone/Tesseract; Mind Stone/Loki's scepter/Vision's forehead; Reality Stone/Aether; Power Stone/Orb; and Time Stone/Doctor Strange's Eye of Agamotto -- with only the Soul Stone left to be found. In the film, Thanos' search for the Infinity Gauntlet's final Stone takes him to the planet Vormir, in the Kree Galaxy. We also learn that the Mad Titan originally tasked his daughter Gamora with retrieving the Soul Stone, but she kept its location a secret from him. It's only when her sister Nebula is being tortured by Thanos that Gamora reveals its location.
As Gamora and Thanos make their way to the top of a high cliff, they're greeted by a mysterious hooded figure who is the keeper of the Soul Stone. After delivering some cryptic messages, the figure steps into the light to reveal himself to be none other than Hydra's former leader, the Red Skull, with Ross Marquand replacing Hugo Weaving in the role that.
The Red Skull was last seen in 2011's Captain America: The First Avenger after seemingly dying from an explosive blast by the Tesseract/Space Stone. What made this apparent death curious was how the light show produced by the Tesseract resembled the Asgardians' Bifrost, which is their "magical" method for instant transportation across reality. What's more, Red Skull's appearance in Infinity War indicates that the villain has spent the last 70 years in deep space following the climax to The First Avenger.
The villain fills Thanos in on his knowledge of the Infinity Stones, how he sought them himself and even held one, though Red Skull's current situation can be blamed for his decades-long exile. The most important information that Red Skull provides Thanos is the Soul Stone will only present itself once the sacrifice of someone you love is made -- a soul for a soul. Therefore, Thanos sacrifices his favorite daughter Gamora in order to obtain the Soul Stone.
A rumor circulating as far back as February hinted that Red Skull would have a role in the film. Some fans saw that theory bolstered by Marvel's Avengers: Infinity War Prelude #2 comic, which touched upon the previous appearances of the Infinity Stones in the MCU, and seemingly made the Red Skull's fate in The First Avenger less ambiguous. Of course, now that Red Skull is confirmed to still be alive, this opens the door for him to be an antagonist in Phase Four and beyond. Plus, with him being found in space, Red Skull doesn't have to be relegated to Earth-bound stories, and could appear in future Guardians of the Galaxy films or other galactic entries in the MCU.
Directed by Joe and Anthony Russo, Avengers: Infinity War stars Robert Downey Jr., Chris Evans, Chris Hemsworth, Mark Ruffalo, Jeremy Renner, Scarlett Johansson, Paul Bettany, Anthony Mackie, Paul Rudd, Elizabeth Olsen, Tom Holland, Benedict Cumberbatch, Chadwick Boseman, Chris Pratt, Zoe Saldana, Dave Bautista, Bradley Cooper, Vin Diesel, Tom Hiddleston and Josh Brolin, among others. The film is now in theaters worldwide.