When it comes to casts, Thor: Ragnarok has a pretty great one. Not only does it have the always charismatic duo of Chris Hemsworth and Tom Hiddleston, but the cast also includes Mark Ruffalo, Cate Blanchett, Jeff Goldblum, and Tessa Thompson. Even with a cast this stacked, director Taika Waititi wanted to add a little extra Marvel flavor into the mix. Waititi wanted to bring in a character from Guardians of the Galaxy, but wasn't able to make it work. What's most surprising, though, is the character he wanted.
On Saturday, Taika Waititi did an AMA on Reddit where people could ask him any questions about his career and upcoming projects. Everybody mostly wanted to know more about Thor: Ragnarok, and one question was if there were any characters he wished had been in the movie but weren't. Waititi revealed that he wanted to include John C. Reilly's character from Guardians of the Galaxy, but the logistics weren't possible.
In Guardians of the Galaxy, John C. Reilly played Rhomann Dey, an officer in the Nova Corps. He had a history with Star-Lord, arresting him for petty theft and then again when he fought Gamora, Rocket Raccoon, and Groot over the Orb. He was largely responsible for convincing the Nova Corps to help the Guardians defend Xandar against Ronan because he believed that nobody is "100% a dick." Dey has a family that was saved by Rocket during Ronan's attack, and he see's the Guardians off at the end of the movie with their wrap sheets cleared.
Including Rhomann Dey in Thor: Ragnarok is an interesting choice given some of the other bigger characters in Guardians, but it does make some sense. Dey is not a very large role, so it's easier for him to appear in other films, sort of like a space version of Agent Coulson. He's not important enough to take the spotlight away from the leads, but big enough that fans would appreciate seeing him. Plus, it doesn't hurt that he's pretty funny too.
As to why getting Rhomann Dey into the movie didn't work it could have been something as simple as Reilly's schedule, or that it didn't really make much sense to the story. One of the only ways I can see Dey appearing in Ragnarok is if Thor was visiting Xandar to make sure the Power Stone was properly safe and Dey was his guide.
John C. Reilly may not be in Thor: Ragnarok, but a lot of other great actors are, and you can see them when the film hits theaters on November 3, 2017.