Dan Aykroyd originally wrote 'Ghostbusters' with stars John Belushi, John Candy, and Eddie Murphy in mind for the roles of Peter Venkman, Louis Tully, and Winston Zeddemore, respectively. But Belushi passed away before they could make the film, and Candy couldn't commit to his role -- as for Eddie Murphy, he chose to star in 'Beverly Hills Cop' instead. 'Ghostbusters' was temporarily the highest-grossing comedy of all time that year, but when 'Beverly Hills Cop' was released just a few months later, it knocked 'Ghostbusters' off the throne.

Perhaps it was for the best that Eddie Murphy didn't star alongside Bill Murray, Harold Ramis, and Dan Aykroyd in the paranormal comedy classic -- Murphy has a larger-than-life screen personality, and the film needed actors that could share the screen and the laughs.