Two movies I loved when I was growing up, and still enjoy very much to this day, could have turned out incredibly different indeed. The role of Emmet Fitz-Hume in Spies Like Us, as played by Chevy Chase, was originally written for John Belushi. And the role of Peter Venkman in Ghostbusters was too. I find it hard to imagine anyone else in either role.
Here’s Dan Aykroyd and John Belushi talking about their recent release Neighbors, and mentioning their new project about two spies working for the DOD.
http://youtu.be/HWNdweemVyc
And here’s Bill Murray talking about SNL, working with Ivan Reitman, Ghostbusters, and Belushi (answering a question about Wired by the sounds of it):
http://youtu.be/5DDFcdLBgmY
And here’s an article about a script written for Belushi that was never made, called Noble Rot.