On Saturday, one of the best shows ever on television airs for probably the last time, as the Sci-Fi Channel draws the curtain on "Mystery Science Theater 3000."

Photo © Copyright Best Brains, Inc. From left, Crow, Mike Nelson (Michael J. Nelson) and Tom Servo of ''MST3k.''

New episodes of "MST3K" ended five years ago, but the show continues in reruns. However, Sci-Fi has allowed its contract with Best Brains, the producers of "MST3K," to run out, meaning that this week's episode, "The Screaming Skull," will be the last on Sci-Fi. And unfortunately, it is unlikely that another cable outlet, never mind broadcast channel, will pick up the series. Not only would the channel have to pay for the rights to "MST3K," it would have to renew the rights to the films shown and ridiculed on the series. That makes airing "MST3K" repeats too expensive given its devoted but small following.

Originating on Comedy Central, "MST3K" turned the heckling of bad movies into an art form. Trapped aboard an orbiting space station called the Satellite of Love, Joel Robinson (Joel Hodgson) and his robot pals, Crow and Tom Servo, were forced to watch bad movies as part of an ongoing science experiment. (We in the TV audience, of course, got to watch Joel and the bots watch the movies.) The perpetuators of all this were mad scientist Dr. Clayton Forrester (Trace Beaulieu, also the original voice of Crow) and hapless assistant TV's Frank (Frank Conniff).

A lot of things changed during the show's 10-year run. During season 5, Hodgson left and was replaced by Michael J. Nelson, also the show's head writer. Nelson played a character named, oddly enough, Mike Nelson. After season 6, TV's Frank died for the last time (don't ask) and went to Second Banana Heaven. Then there was that big move from Comedy Central to Sci-Fi, which came with season 8.

Other characters came and went, too. Dr. Forrester evolved into a Star Baby (think "2001: A Space Odyssey"), so new tormentors were needed. They arrived in the form of Dr. Forrester's mother, Pearl (Mary Jo Pehl); an omnipotent but put-upon extraterrestrial (Bill Corbett, also the new voice of Crow); and a talking ape named Professor Bobo (Kevin Murphy, the voice of Tom Servo).

While dealing with the least of popular culture, "MST3K" assumed the most of its viewers. How many other TV shows would expect, or at least hope, for someone in the audience to get a joke comparing a character in a bad movie, in this case "The Touch of Satan," to German orchestra conductor Herbert von Karajan (1908-1989)? Not many, I bet.

"MST3K" was appointment viewing for many aficionados of bad movies, which is ironic, because the show's cast and crew were, and seemingly still are, ambivalent about the movies they skewered. After "MST3K" ceased production, Nelson published a hilarious collection of reviews called "Mike Nelson's Movie Megacheese," so he is OK in my book. But the Dark Side has seduced Murphy. He can be found lurking in art-house theaters around the globe (see his book, "A Year at the Movies") or, worse still, heard on National Public Radio reviewing tedious art films.

But once you've started talking during movies, it's hard to stop. Nelson, Murphy and Corbett are working with Legend Films to provide commentary tracks for some new DVD releases. Nelson will do the dishonors for Legend's upcoming "Reefer Madness" disc, due April 20.

Speaking of DVDs, Rhino Home Video continues to release "MST3K" episodes. So far, 10 single-episode DVDs and four four-episode box sets are available, with a fifth box set scheduled for release on March 9.

So, even if "MST3K' is gone from the airwaves, it isn't really gone — not as long as there are bad movies and people to poke fun at them.

The final "Mystery Science Theater 3000" airs Saturday at 8 a.m. Central.