It will not be Vin Diesel, but Paul Bettany to play the role of The Vision. The world knows him better as the voice of Jarvis from the Iron Man Trilogy. Jarvis is of course Tony Stark’s (Robert Downey Jr.) helpful A.I. system. His transformation into the android Avenger happens in Avengers: Age of Ultron!
Variety had the official word: “Production starts next month, with director Joss Whedon and cast members like Robert Downey Jr. and Chris Evans. The Vision was an android created by the robotic villain Ultron, who was meant to be one of Ultron’s henchmen but who instead turns against him and becomes a hero”.