4. The Rock - Charlie And The Chocolate Factory
Looking back on it, it's difficult to picture anyone besides Johnny Depp playing the second-coming of Willy Wonka in Tim Burton's manic version of Charlie and the Chocolate Factory. But things at Wonka Factory would have been just a wee bit different if Depp had backed out, because Burton's second choice for the mad candyman was none other than The Rock. This could be a case where Burton was simply using a wild card backup actor to convince the movie studio to use his primary choice. After all, as hard as it might have been to sell the higher-ups on the idea of Depp as Wonka, threatening them with the possibility of Johnson in that role likely got them to green-light his initial idea pretty quickly. ...And yet, part of the world weeps at this incredibly weird missed opportunity.