Dwayne 'The Rock' Johnson MUST be cast as THE BOULDER. 
The Boulder was originally inspired by real-life pro wrestler Dwayne 'The Rock' Johnson, who, like THE BOULDER, refers to himself in the third person when he speaks. According to the Avatar Extras for "The Blind Bandit", the production team tried to get Dwayne Johnson to voice THE BOULDER, but they were unable to do so, and he was eventually voiced by pro-wrestler Mick Foley, a good friend of The Rock. (Source: Wikia)

This is crucial to the success of this live adaptation.