Casting rumors have started up about the new Man of Steel sequel, including who might play Superman's nemesis Lex Luthor.

Lex Luthor has not been confirmed to be in the new film, but a source at DC Entertainment told Cosmic Book News recently that he would "definitely" be in the sequel. As for who will play the villain, there is one contender that seems to be the frontrunner.

Mark Strong, famous for supporting roles in such films as Sherlock Holmes, John Carter and Tinker Tailor Soldier Spy, is the leading contender to play Luthor, according to a recent report from MovieWeb. The report stated that Man of Steel 2 director Zack Snyder and Warner Bros. want Strong to play the role.

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One thing that may work against Strong being cast is that he already played the villain Sinestro in the DC Entertainment film Green Lantern. If they are going by the rules of the "DC Cinematic Universe," producers may not want to cast the same actor for another important, villainous role.

If producers do not go with Strong, sci-fi film site Shadowlocked offered a few more suggestions for actors that could play Lex Luthor. One of the leading suggestions was Jason Isaacs, who played Lucius Malfoy in the Harry Potter film series. Another suggestion was Billy Zane, who played the villainous Cal Hockley in Titanic. The article noted that the egotistical nature of his character in Titanic could translate well to Lex Luthor.

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Since Man of Steel 2 was announced to be "Batman vs. Superman," there has also been a lot of speculation about who will be playing Batman opposite Superman's Henry Cavill.

Enstars previously reported that producers might be looking at Teen Wolf star Tyler Hoechlin to play the Caped Crusader. Cosmic Book News reported that producers were likely going to choose an actor of similar career standing as Cavill, who was relatively unknown before taking on his Superman role in Man of Steel.

Watch the most recent version of Lex Luthor, as played by Kevin Spacey in 2006's Superman Returns:

Tags: Man of Steel 2 Batman vs. Superman Mark Strong