There's been plenty of speculation over Vin Diesel's involvement with Marvel. First (and quite some time ago), he uploaded a fan made photo of him as Vision to his Facebook page (and an official image or two of the character afterwards), and more recently, he announced a meeting with Marvel. While there, he took a photo right in front of THE AVENGERS #2. Needless to say, there's been a lot of talk about who the star could become in Marvel Studios' expanding universe. Well, today the actor changed his Facebook cover photo to the following image of Groot and it seems safe to assume we can now put that casting speculation to rest.
Sure, he's used another character as his cover photo before, but he specifically stated the last one was fan made and the timing for this totally matches all of the casting announcements and hype they're trying to build for this movie. Assuming this is indeed his role, it shouldn't come as much of a surprise because the dude has quite the voice (Iron Giant, anyone?).
Viners, would you be cool with Diesel as Groot or would you rather have him as another character? Guardians of the Galaxy is directed by James Gunn and scheduled to hit theaters 08/01/14.
UPDATE #1
Vin Diesel has already changed his cover photo. Perhaps he let the alien out of the bag too early?
UPDATE #2
Deadline claims the actor is indeed in talks with Marvel for the role of Groot.