Immediately following the Hulk's appearance in 2015's Avengers: Age of Ultron, the green-skinned Avenger wasn't seen much in the MCU. However, the Hulk made a huge splash three years later with his return to Marvel Studios in Thor: Ragnarok. The Jade Giant had relocated to the planet Sakaar, where he took part in the Grandmaster's Contest of Champions.
The character's presence far out in the cosmos came as a surprise to some fans, but it was actually a development lifted straight from the comics. However, things in the MCU played much differently than they did in the original Planet Hulk storyline. Here's a rundown of how the Hulk found himself on Sakaar in the source material, what happened as a result, and how it compares to what was seen on the big screen.
The Plan of Marvel's Illuminati Went Off-Course in Planet Hulk
In the comics, it was Marvel's Illuminati who triggered the events of the Planet Hulk story. The group, which included the likes of Iron Man and Mister Fantastic, worked in the shadows of the Marvel Universe for years, making decisions and shaping events in secret.
After the Hulk went on another dangerous rampage, the Illuminati arranged for Hulk to be taken far away from Earth, where he couldn't hurt anyone any longer. Their goal was for Banner/Hulk to be taken to a quiet planet where he could live peacefully and not hurt anyone. However, the shuttle carrying him was knocked off course, and he ultimately found himself on the planet Sakaar.
The Hulk Left Earth on His Own in the MCU
In the MCU, things were a lot different. The Hulk disappeared at the end of Avengers: Age of Ultron in a quinjet, not wanting to be a danger to anyone else or be used as a weapon. He willingly blasted off into space, and, given the large number of wormholes that led to Sakaar, his ship eventually landed on the Grandmaster's planet. While there, he remained in complete control of Banner for two years.
These circumstances are completely different from the source material, where it was other characters who tricked him into leaving. This makes the Hulk a more conscientious and heroic figure in the MCU. What's more, it set up a Planet Hulk adaptation without tarnishing the Hulk's relationship with Earth's heroes.
After all, the Illuminati's betrayal of the Hulk originally served as a building block to World War Hulk. In the case of the MCU however, no betrayals occurred, and no friendships were broken. It was a more organic turn of events that didn't see fan-favorite heroes turn on one of their own.