He may be playing Groot in Guardians of the Galaxy, but that wasn't Marvel's original plan for Vin Diesel.
Despite being known mostly for voicing the Iron Giant and playing Riddick, Diesel is actually a pretty versatile actor. Marvel recognized this when they first had him come in to talk about his potential involvement in their upcoming movies.
Despite his voice-acting ability, Groot was not the original intent for Diesel. Instead, there was the possibility that he'd get a franchise all his own. According to Diesel, "What we were originally talking about was a fresh IP (intellectual property), and that was the focus of our conversation."
Which has us wondering who he might have originally been tapped to play. Doctor Strange? Iron Fist? Ant Man? Even his wording is interesting. Could Marvel be considering creating movies based on brand-new characters and then retroactively incorporating them into comics?
Meanwhile, Diesel isn't definitely Groot yet. He's still got to work it out. "It's still up to my reps to allow that to happen," says Diesel. That probably boils down to time and money, but, considering how much he's talking about it, we're pretty sure Diesel will find a way to be Groot.
(via Comic Book Movie)