Confirming a story that surfaced in May, Deadline has been given the word that Marvel has tapped John C. Reilly to play "the Agent Coulson of the Guardians movies", Nova Corps leader Rhomann Dey, in Guardians of the Galaxy.
Here's what Brendon had to say on this subject a couple weeks ago:
First of all, let's address Rhomann Dey. According to HitFix, Marvel have made an offer to John C. Reilly to take this part, "the Agent Coulson of the Guardians movies." In the comics though, Dey is the head of the Nova Corps. and not a human being from planet Earth. Why the change? Well, it looks like they've mixed up some elements of his storyline, which originally saw him select Earthling Richard Rider to join the Nova Corps. It's not clear, as yet, but those story pieces seem to have been rewoven somewhat…
What's more, Dey will have a key liaison back on Earth and, while Marvel haven't settled on any actor yet, they've apparently been looking at Hugh Laurie, Alan Rickman, Ken Watanabe… basically, anybody filed under A for Authorative at Casting Central.
We do know that the Nova Corps. are in the film, and not just because Nova ships appeared in some of the concept art. It seems they've been reworked, as you might expect, but it worked – is still working, and will continue to work, I expect, with SHIELD, so I see no reason to worry.
Just because the film is going full-on Galactic, it doesn't mean we won't be seeing any of the characters from previous Marvel movies. Nick Fury, for example, is set to play an important part when he convinces Groot not to experiment on the human race but to respect and assist them instead. Drax still has his human origins, having been a saxophone player called Art who was killed by Thanos in the Mojave Desert.