After his exit at the end of Avengers: Age of Ultron, many have speculated when Bruce Banner (Mark Ruffalo) and his alter-ego, the Hulk, might next appear in a Marvel film. We have been told by Feige that he would appear at least one in Phase Three before Avengers: Infinity War Part I arrives in May 2018, but not much else has been said. For a time there was heavy speculation that he might factor into Captain America: Civil War in some capacity, but that no longer seems to be the case. Other had hoped he might appear in Guardians of the Galaxy Vol. 2, be it in a “Planet Hulk“-esque fashion or some other way, but director/writer James Gunn nipped that rumor in the bud almost immediately. So long as Gunn runs the Guardians films, there will be no Terrans (aka “humans from Earth”) in them other than Peter Quill (Chris Pratt).
Appearances in Scott Derrickson’s Doctor Strange or Jon Watts’ still-untitled Spider-Man film could be fun, but I suspect Marvel doesn’t want to crowd the debut films of their latest round of “new” heroes (which also includes Black Panther and Captain Marvel) with the Hulk and all of the baggage he brings with him. That leaves Taiki Waititi’s Thor: Ragnarok and guess what! That’s where he’s apparently headed. According to JoBlo, the big fella will be re-appearing somewhere within Thor’s penultimate adventure.
The site paints a picture of the green incredible one being found on another world that is neither Earth nor Asgard. How did he get there? After all, when last we heard of him, his Quinjet had splashed down in the ocean near a small island, with his teammates assuming he was isolating himself there from humanity. What has seemingly taken him across the galaxy (if not the universe)? Assuming this portion of the rumor is true, we do not know. We also don’t know much Hulk will be in the film or how important he is to the plot.
Some sites are going so far as to assume that Hulk will be practically co-leading the film with Thor, but I’m not so sure. After all, most rumors involving his once-potential turn in Civil War only had him appearing in a post-credits sequence. If that has been moved and/or altered, it stands to reason that he might only be appearing in the same capacity here. Also a big assumption is that this “other world” means another planet. Everyone has such a hard-on for the possibility of a Planet Hulk movie that they are ignoring the simple fact that it just doesn’t fit.
Whatever Hulk does between now and Infinity War, he still has to be around for Infinity War. There’s no time or room to tackle Planet Hulk in the interim, especially in Ragnarok, which is not only the biggest catalyst for Infinity War, but also has to serve as a trilogy capper for Thor. Planet Hulk is something that I think will happen someday in the MCU, but not until after Phase Three and likely not until Marvel regains full solo film rights for the character. If he’s not on Earth and not on Asgard, but also not off on some alien world, then where could he be? Another Asgardian realm is a possibility. Perhaps he will be transported to and/or trapped in Hel or Niffleheim, trapped in what are effectively Hell or Purgatory by the likes of Loki and/or Thanos? This is both more in keeping with Thor’s solo tales and more fitting a place for him to reside until his return in Infinity War, as it doesn’t involve space travel for him to be retrieved (by Thor or Doctor Strange) or return of his own accord.
Bottom line? It’s just way too early to tell. We know very little about Thor: Ragnarok and that will likely remain true until we get closer to its start of production. As of now we simply know that it is the culmination of Thor’s trilogy, it will likely feature the destruction of Asgard and the deaths of some of our favorite characters, and Natalie Portman likely will not be returning. As it stands, the cast of the film is now as follows: Chris Hemsworth, Tom Hiddleston, Anthony Hopkins, Jamie Alexander, Ray Stevenson, Zachary Levi, Tadanobu Asano, Idris Elba, and now Mark Ruffalo.