Chris Hemsworth, Scarlett Johansson to lead voice cast of 'Transformers' animated prequel

'Variety' reports that Hemsworth, Johansson and Brian Tyree Henry will voice main characters in 'Transformers One'. Hemsworth will voice Optimus Prime, Henry will portray a young Megatron and Johansson will voice Elita, a G1 Autobot. Additional cast members include "Keegan-Michael Key as Bumblebee, Jon Hamm as Sentinel Prime and Laurence Fishburne as Alpha Trion," 'Variety' reports. Ramsey Naito, president of Paramount Animation and Nickelodeon Animation, made the announcement at CinemaCon. "I'm so excited and proud to be working with Hasbro and eOne to bring the first animated 'Transformers' movie to theaters for a never-before-told story."