Nickelodeon never knew what to make of "Invader Zim." It wasn't like the network's other cartoons. It was twisted. It was subversive. It was dark. Sometimes it was downright mean.

It was the best thing on television.

But it wasn't what Nickelodeon's programming executives expected. So, of course, they moved it from one timeslot to another and, finally, canceled it outright after one season. But by then it was too late. The damage was done. "Invader Zim" had accumulated a rabid cult following.

Which explains why "Invader Zim Vol. 1: Doom Doom Doom" has been sitting comfortably among Amazon.com's 50 top-selling DVDs for the past several weeks, putting it ahead of other Nickelodeon DVDs.

Released by Media Blasters under its Anime Works label, "Invader Zim Vol. 1" is the first of three two-disc collections that will encompass the entire series, including the Christmas and Halloween specials. The first set includes the first nine episodes, the unaired pilot, commentaries on selected episodes and interviews with cast members. The only thing missing is an interview with series creator Jhonen Vasquez, which Media Blasters may be saving for one of the future sets. Vasquez, however, is an active part of the episode commentaries.

But by now, some of you are wondering, just who or what is "Invader Zim," anyway?

Zim (voiced by Richard Horvitz) is a short, temperamental and extremely hyperactive extraterrestrial who believes that his superiors, the Almighty Tallest, want him to conquer Earth. Actually, they sent him to Earth to get him out of the way. Zim already ruined one invasion plan, Operation Impending Doom, and they don't want him to ruin Operation Impending Doom 2.

Zim, you see, isn't too bright. And to make matters worse, the Almighty Tallest have given him a robot helper, Gir (Rikki Simons), who is anything but helpful. But Gir is cute, especially when zipped up in his doggie disguise.

On Earth, Zim disguises himself, unconvincingly, as a human child and goes to school to learn more about these strange Earthlings who surround him. At school he encounters his worst enemy, Dib (Andy Berman), a nerdy outcast who has seen a few too many episodes of "The X-Files" and dreams of getting Zim on an autopsy table.

One of the highlights of the first DVD set is the episode "Germs," in which Zim watches an old sci-fi movie and becomes convinced that Earth's germs are out to kill him. By the end of the episode, he is wandering around like Howard Hughes, wearing kitchen gloves and putting boxes of tissues over his shoes.

In "Attack of the Saucer Morons," Zim has a close encounter with UFO enthusiasts who believe that Zim's crashed spaceship brings a message of love. After this episode, you will believe a pig can fly.

And in "Dark Harvest," Zim decides he must become more human if he is to avoid capture. So, he steals organs from his classmates, leaving behind common household items. Can Dib escape before Zim replaces his spleen with a TV remote?

Media Blasters has done an excellent job with this first set, and the show's fans will appreciate all of the bonus features, especially the commentaries, which are funny if not particularly informative. Any time you have more than three people on the same commentary track, you get nothing but chaos.

One thing that does come through, however, is Vasquez's ambivalence about his creation. "Invader Zim" may have earned him a cult following, but the process of making the show seems to have been a strain for the writer/cartoonist, who before "Invader Zim" was best known for his comic book, "Johnny the Homicidal Maniac."

Still, his pain is our gain.

"Invader Zim Vol. 1: Doom Doom Doom" retails for $24.95.