Alfred Gough, executive producer of The WB’s Superman-as-a-teenager drama "Smallville," said the late Christopher Reeve’s recurring character, Dr. Swann, will pass away in an episode airing later this season.

Margot Kidder, who’s already filmed two episodes as Bridgette Crosby, Dr. Swann’s emissary, will continue as a link between the young Superman (Tom Welling) and Dr. Swann’s research about the teen’s alien origins. Kidder played Lois Lane opposite Reeve’s Clark Kent in the "Superman" movies.

Reeve’s Dr. Swann, a brilliant scientist, revealed to Clark that his home planet of Krypton had been destroyed.

Kidder was brought in after Gough spoke to Reeve this summer about appearing again on the series, but Reeve was directing a film and unavailable for the season premiere.

"We thought she was a good person to help fill in around Dr. Swann, give him some other people [to work with]," Gough said yesterday, "and our plan was to bring Chris back later in the season and have him in a scene with Margot and Tom."

Now Kidder’s character will carry the Dr. Swann story forward.

"It won’t have a hugely dramatic effect on our story lines, because, with the introduction of Bridgette Crosby, it still gives you a link to that person," Gough said. "But there is some key information he was going to provide, so now she’ll provide it."

Tonight’s "Smallville" (8 p.m., WCWB) will begin and end with brief tributes to Reeve.