Harrison Ford was once in line to play Mission: Impossible - Ghost Protocol's main villain, but here's why Tom Cruise ruled out his casting. While Cruise might be the undisputed star of the franchise, that wasn't necessarily a given when Mission: Impossible - Ghost Protocol was greenlit. Cruise's popularity and bankability had taken something of a hit following the third movie, so when development on the fourth entry commenced, it was planned that Jeremy Renner's - who was then coming off the back of the acclaimed The Hurt Locker - character Brandt would be introduced as Ethan Hunt's replacement.
While Paramount gave a greenlight to Mission: Impossible - Ghost Protocol (which features Tom Cruise's unforgettable Burj Khalifa stunt) with this in mind, director Brad Bird and his creative team didn't take the mandate very seriously. As production progressed, it was clear that Cruise was still very much the star of the series, and plans for Ethan to retire at the end and become the new IMF secretary slowly faded into the background. Mission: Impossible - Ghost Protocol received great reviews and helped revitalize the entire series, with Mission: Impossible 7 and 8 currently on the way.
If there's one weakness to Mission: Impossible - Ghost Protocol, it's that the antagonist is poorly fleshed out. The late Michael Nyqvist played Kurt Hendricks, a scientist who determines the world will eventually destroy itself via nuclear war, so he opts to kick one off early so the survivors will learn the error of their ways and unite. Hendricks has little screentime and aside from a showdown with Tom Cruise's Ethan Hunt in a very unique parking lot, few standout scenes. The lack of screentime for the role might be a consequence of how it was originally developed, as producer J.J. Abrams envisioned Harrison Ford playing the role, with his casting kept secret and the villain only emerging in the third act.
In an episode of the Light The Fuse podcast, Mission: Impossible - Ghost Protocol screenwriters Josh Applebaum and André Nemec opened up on Ford's potential involvement. Apparently, Mission: Impossible - Ghost Protocol's Harrison Ford casting was coming along nicely, with the actor being into the idea. The writers put the nixing of Ford's Ghost Protocol casting down to Mission: Impossible movie lead Cruise himself, who stated that while it would be amazing to have the actor be part of the sequel, audiences probably didn't want to see him and Ford beating each other up.
Had he been cast, Harrison Ford's Mission: Impossible - Ghost Protocol role would have also been a dark version of Hunt, and the kind of character Ethan could evolve into if he lost his way. Ultimately, the idea of Harrison Ford's Mission: Impossible - Ghost Protocol casting was abandoned, and the character was re-written into the Michael Nyqvist character. While Cruise had a point about Ford's casting, it still would have been fun to see the two actors together onscreen.