This is what they had to say about the departure. Joint statement from “Smallville” Executive Producers Darren Swimmer, Todd Slavkin, Kelly Souders and Brian Peterson; The CW Network; and Warner Bros. Television regarding Michael Rosenbaum’s departure from “Smallville”:

“It has been an honor and pleasure to work with Michael for the past six seasons. He is one of the best actors on television and has never failed to bring a new layer to the character of Lex Luthor in every episode. While Michael won’t be a series regular and we won’t have the pleasure of working with him on a weekly basis this fall, we like to think that we haven’t seen the last of Lex Luthor. Stay tuned.”

It does make sense, since Lex needs to start is real road to villainy, yet we will miss the actor.