http://www.ranker.com/list/good-actors-and-actresses-who-sucked-as-villians/villain123,
Al Pacino in Dick Tracy
Oliver Platt in Year One
Sharon Stone in Catwoman
Danny DeVito in Batman Returns
Possibly the worst of all time, the Penguin in Batman Returns wasn't scary, just plain gross. Played by Danny DeVito.
Christian Bale in Shaft
John Lequizamo in Spawn
John Travolta in Battlefield Earth
Kenneth Branagh in Wild Wild West
Dennis Hopper in Super Mario Brothers
Samual L. Jackson in The Spirit