Michael Rosenbaum, who played Clark Kent's arch nemesis Lex Luthor on Smallville, is leaving after this season.
Rosenbaum, 35, had been in contract negotiations for months. Producers hoped he might consider limited appearances on the long running young Superman series.
"It is time for me to start the next chapter of my life and career," Rosenbaum said. "I hope that I gave you some enjoyment over the years and that you found my portrayal of Lex Luthor to be satisfying."
While Rosenbaum hopes to let his hair grow out, producers have lined up not one - but two- count 'em - super villains to combat Clark in his never-ending battle for ratings.
One big bad is Doomsday who managed to kill off Superman a few years back in the DC comics universe.
The other is a mysterious femme fatale whose "attraction with Clark may prove to be as deadly as kryptonite for him."