"Smallville" is getting a ninth season, but don't expect "Supernatural" to go that far.

Eric Kripke doesn't care what the ratings are on The CW ... after the fifth season, he's done.

"Despite what the network and studio may or may not want, I don't have more than five seasons of a story," Kripke told Entertainment Weekly, according to the New York Post. "I would be willing to make sure there are enough villains and heroes around to continue a new story, but there's no way I'm doing Season 6."

The show is concluding its fourth season, and The CW has already enthusiastically renewed it for a fifth season. But even if Kripke does leave, it doesn't necessarily mean the end of "Supernatural." When Al Gough and Miles Millar left "Smallville," The CW renewed the show anyway, and ratings and critical acclaim has remained strong.

However, Kripke might not be alone in how many seasons the show should last.

"We don't live at home," said Jensen Ackles, one of the stars of the show, about how "Supernatural" is shot in Vancouver, British Columbia. "We don't sleep in our own beds. Our families aren't here. Our friends aren't here. Our girlfriends aren't here. To do it for another five years, I don't know if I could handle it."

Jared Padalecki, the other half of the Winchester Brothers, agrees ... but with slightly different reasons.

"I don't want to be cheese, and here's Sam and Dean at age 50 sitting in wheelchairs," Padalecki said. "I'd rather leave [fans] wanting more than get to the point where they boo you off stage."

"Supernatural" airs Thursdays at 9 p.m. ET on The CW.