The "Transformers 3" cast is made up of veterans of the series who have returned for one more go around. One member of the "Transformers" cast that will not be returning is Megan Fox who had about as public a feud with her director as you're likely to see. Fox and Bay traded barbs over Twitter, the Internet and a few Western Union telegrams until it was decided the "Transformers 3" cast would move forward with a new leading lady.
LaBeouf has long been one of Hollywood's hot young stars. He joins the "Transformers 3" cast as one of the real stars of the series having been a central character in all three films as Sam Witwicky, the human friend to the Autobots. Despite being relatively young LaBeouf has appeared in 41 different movies and TV shows including taking a turn in the "Indiana Jones" series of films.
Whitely joins the "Transformers 3" cast as a newcomer in a central role. Whitely will play the new love interest of Sam Witwicky. A Victoria's Secret model by trade, this is the first film Whiteley has appeared in.
Duhamel joins the "Transformers 3" cast as a member of the military who learned of the Transformers' existence in the first film. His character has served as an ally to the Autobots throughout. Duhamel is probably best known for his role on the long running series, "Las Vegas."
Cullen returns to the "Transformers 3" cast as the voice of the Autobot leader Optimus Prime. While Cullen is certainly the lesser known regular of the cast, his participation in this project is special because he is the voice actor that actually voiced Optimus Prime in the original "Transformers" series that was animated. He is the only member of the cast that can boast going back with the franchise that far.