Shia LaBeouf is ready to take the key out of the ignition of the Transformers franchise, insisting he's done with the hugely-successful action series.

The former child star cemented himself as a leading man in Hollywood by fronting the first film in the blockbuster franchise in 2007, and now he's preparing for the release of the third Transformers movie, which will be released this summer.

But he's adamant it will be his last outing as Sam Witwicky.

He tells MTV.Com, "For sure (this will be my last). I'm not coming back to do another one. I don't think (director) Mike (Bay) will either."

But he's convinced studio bosses will bring back the franchise with another star in the lead role: "It is still a hot property, I think, especially coming out of the third one. So, I imagine they'll reboot it at some point with someone else."

Megan Fox has already quit as LaBeouf's leading lady in the films - she has been replaced by British model/actress Rosie Huntington-Whiteley for the new movie.