Michael Rosenbaum returns to Smallville for its finale. As seen here, he reprises the role of Lex Luthor.
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Lux Luthor will return for the final episode of Smallville. The character is played by Michael Rosenbaum.
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A picture of Michael Rosenbaum as Lex Luthor on Smallville. He was a major character until season seven.
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Smallville Quotes

When we first met Black Canary she was nothing more than Lex Luthor's little organ grinder monkey. I mean, do you ever look to see who the bad guys really are before you start throwing knives and spin kicks there chickadee?

Lois

Like they say, you can't go home again.

Clark Luthor