Hugh Jackman – X-Men:
It wasn't easy casting the role of Wolverine, first offered to Russell Crowe, who passed — and Dougray Scott got the part. But scheduling conflicts with "Mission: Impossible 2" forced Scott to drop out, so Singer turned to Hugh Jackman, who joined three weeks into production. Six films later, Jackman's a superstar. Scott, meanwhile, is filming something called "The Vatican Tapes."
These last-minute switches worked out for the best — will the same be true for Charlie Hunnam’s replacement in ‘Fifty Shades of Grey?’