George Miller spent several years developing Mad Max: Fury Road, and one version of the movie would've starred Heath Ledger. Development hell is a term thrown around quite a lot for movies that just can't seem to get off the ground and, for a long time, it appeared a fourth Mad Max movie would remain stuck there. Miller began developing the film in 1998, a few years after he re-acquired the rights to the franchise he helped make so popular.
From that point on, it didn't take long for Mad Max: Fury Road to pick up steam. Production was ready to begin in 2001 but was postponed after 9/11, forcing Miller to move to Happy Feet instead. Plans for the movie picked back up in 2003 and filming was once again ready to go in Australia. Unfortunately, the locations they were going to film at were ruined by the weather, leading to another delay. All of these hurdles just to get production underway didn't even address the burning question of who would star in the movie.
What was decided by Miller was that Mel Gibson would not be back to star to keep Max in an effort to keep him younger. While Tom Hardy eventually took the role, Heath Ledger was Miller's first choice to be Max. The possible casting of Ledger for Mad Max: Fury Road is something that intrigued both he and Miller greatly, but was never finalized. Miller has said in interviews that the two of them talked about Ledger playing Max multiple times prior to his death in 2008.
Although this version of Mad Max: Fury Road never happened, this could've been a huge get for Miller at the time and an interesting career move for Ledger. The timing of their discussions happened before the release of The Dark Knight, where Ledger delivered an outstanding performance as Joker. If Ledger had committed to the role, it is difficult to imagine that Mad Max: Fury Road wouldn't have sped through development from that point forward to capitalize on Ledger's elevated stardom. As for why Miller was interested in Ledger to begin with, he told The Daily Beast that Ledger had the "maleness, charisma, and restless energy" to properly play Max.
As fascinating as it would be to see Ledger take on this role, Miller's persistence to make the movie after his death paid off. He spent several years filming and editing the movie in the lead up to its release in 2015. Once it finally arrived, audiences were not disappointed with what Miller delivered. Hardy proved to be a great Max, while Charlize Theron captivated audiences with her portrayal of Furiosa. With the two of them in the lead, Miller brought giant set pieces and car chases to the screen that helped make the movie somewhat of a technical marvel. With six Oscar wins and $379 million earned worldwide, Mad Max: Fury Road came together quite nicely in the end.