Sean Connery as the Russian Submarine Commander in Red October. As a matter of fact, has Connery ever had a role that actually tested him as an actor?

Kevin Costner as Robin Hood, definitely. The only good job Kevin has done was as the punk gunslinger in Silverado. In Bull Durham and Dances with Wolves he was the beneficiary of very good scripts.

Jack Nicholson was miscast in As Good as it Gets, but because Jack is Jack, everybody loved him in it anyway. His acting all came early on : he was great in Chinatown and actually was the standout actor in Easy Rider.