Career-wise, it's often not bad to be playing the same character all the time.
For example--Tom Cruise and Will Smith.
Denzel Washington was getting a little fed up with it, though, and has tried to do other types of roles easily.
Speaking of him, he co-starred in a movie called Ricochet with John Lithgow. Denzel was a cop and Lithgow was a crazed serial killer who put together a sick, elaborate revenge scheme after getting out of jail.
Not too bad a movie, but seeing the old guy from 3rd Rock battle a guy to the death in a prison swordfight--using telephone books taped to their bodies as armor--is really damn funny.