Smallville by Lorenzo Agius/The CW Smallville by Lorenzo Agius/The CW

Color us super-shocked. Smallville creators Al Gough and Miles Millar have announced their exit from the series, effective at the end of this season.

Marveling at "seven amazing years," the exec producers "look back knowing that the show will continue into Season 8 without us," they say in an open letter. "After much heartache and debate, we have decided it is time for us to move on."

Giving props to the CW series' "remarkable" production team and "a wonderful cast who we have watched mature with admiration and affection," the duo say, "We have been rewarded with a fan base that is as loyal as it is vocal. We are incredibly proud of our work on this show. We achieved what we set out to do. We never compromised our vision. We leave knowing that Smallville is the longest-running comic-book-based series of all time [and] was featured on the covers of Rolling Stone, MAD Magazine, TV Guide and Entertainment Weekly. The pilot had the highest-rated premiere in the history of the WB [where it originated]. Even in its seventh year, it is still the No. 1 scripted show on the network."

In a joint statement, the CW and Warner Bros. TV say, "Al Gough and Miles Millar have been great partners and instrumental in the development and success of Smallville. While we are sad to see them go, we are very excited to announce that executive producers Darren Swimmer, Todd Slavkin, Kelly Souders and Brian Peterson will helm the show next season. [They] have been writing for the show for the past six seasons, and as producers for the last four years, they have played an integral role in the ongoing creative evolution of the series. As showrunners, they will continue to deliver the compelling storytelling that Smallville fans have come to expect and love."

What brought on Goughlar's abrupt exodus? Their letter offers no details, although one section singles out some peers, saying of one, "When the knives were out, you always had our backs." In closing, the pair say, "To the fans who have stuck with us through the highs and the lows, know this - we never stopped fighting to make this show great."

For those who specialize in reading between the lines, the entire letter is posted in comments.

What's your take on this unanticipated exit? Did the boys simply deem it time to move on (there is a reference to being able to now focus on feature projects), or...? - With additional reporting by Rich Sands

POLL: Does this news have you concerned about Smallville's future?