Eckhart, star of the movie Thank You for Smoking, got the part of the villain in the sequel of Batman Begins.
The 38-year-old will be playing the part of Harvey Dent/Two-Face, a Gotham City lawyer, that turns evil after his face gets disfigured by acid.
This character has been played by Tommy Lee Jones in Batman Forever in 1995.
Batman will be starring Christian Bale, and will be directed by Christopher Nolan. Shooting will begin this summer.