Shia LaBeouf,
Josh Duhamel,
Tyrese Gibson,
John Turturro and
Ramón Rodríguez are set to reprise their starring roles, with
Peter Cullen returning as the voice of
Optimus Prime, and
Hugo Weaving also returning the voice of
Megatron.
Ehren Kruger, who collaborated in the writing of the second film, was said to be again involved in the writing. Despite having initially been confirmed for the film,
with the film already into principal photography,
Megan Fox will not reprise her role. With Fox's character Mikaela being dropped, Sam is now set to be assigned a new love interest, who will be played by English
model Rosie Huntington-Whiteley. Also,
Roberto Orci and
Alex Kurtzman, having written the first two films, will not return for the third installment in the series
, which Orci had earlier somewhat anticipated, fearing the duo would "risk getting stale".
Bay has stated that this will be the last installment in the
series.