What famous comedian turned down the role of Winston in Ghostbusters?

The answer is: Eddie Murphy. Eddie Murphy was initially supposed to be in Ghostbusters, a movie he found out about from Dan Aykroyd while filming Trading Places together, but turned the part down to star in Beverly Hills Cop. He says that not being in Ghostbusters is one of his biggest regrets from the ‘80s. But then we wouldn't have had that excellent keyboard hook from Beverly Hills Cop, nor Ernie Hudson's perfectly balanced performance.Source