"Action," Fox's beautifully brutal spoof of modern-day Hollywood, is fantastic, funny, fascinating, ferocious--F-words being particularly appropriate to this show--but for all its nasty hilarity, a nagging question persists: Is it a satire, or a documentary?

A mean, spleeny sitcom, premiering tonight at 9 on Channel 5, "Action" depicts monsters and madcaps in show business at their most ruthless and venal. And succeeds at it wildly. But some of its characters and situations seem not that much of an exaggeration. Hollywood really does embrace the creepiest creeps of the world and sometimes makes them sinfully rich.

King Creep of "Action" is arrogant producer Peter Dragon, played by Jay Mohr, a zippy stand-up comic best remembered for playing the meanie who fired Tom Cruise at the beginning of "Jerry Maguire." Mohr brings snaky, sharky charm to the role of Dragon, a man whose ego could move mountains and who would take money intravenously if it were available in that form.

Two episodes of "Action" air tonight (the regular time slot will be 9:30). Fox made the pilot available but refused to let critics see the second episode. A strange move, but one must remember that a series with intelligence and wit is pretty much a fish out of water on this network. Perhaps the Rupert Murdoch-owned Fox is making the second episode available only to Murdoch's lousy tabloids.

As the premiere opens, Dragon heartlessly berates a commissary employee on the studio lot for a parking violation, showering him with obscenities, which are represented on the soundtrack by strategically placed bleeps. Reportedly, "Action" was developed for HBO, where obscenities can be left in. Perhaps partly because the series is similar to HBO's late, great "Larry Sanders Show," HBO executives passed. Thus did "Action" come to Fox.

Obviously "Sanders," the brilliant Garry Shandling comedy about life onstage and backstage at a TV talk show, inspired "Action," which may also owe something to the Robert Altman movie "The Player," about a studio executive who manages to make murder a good career move. But "Action" isn't an exact copy of anything, and its willingness to deglamorize Hollywood seems bold in the extreme.

Of course if you are going to portray Hollywood, you have to go to extremes. "Action" does. It is the most daring and outrageous new comedy of the season. Its best lines cannot be quoted in a family newspaper, however, because "Action" stretches the boundaries of language allowed on TV. In this case, the stretching is justified and contributes to the verbal verisimilitude.

Certainly we can assume that those behind "Action" know what they're talking about, since one of them is notoriously obnoxious real-life producer Joel Silver, a vulgarian who specializes in violent action films. "Sanders" veteran Chris Thompson wrote the whirlwind pilot and is officially billed as creator of the show. How much of Dragon's character is based on Silver we can only guess. But surely some of it is.

We follow Dragon through a day of wheelings and dealings climaxed by the world premiere of his new movie "Slow Torture." It appears to be aptly titled, a threat to Dragon's current box-office winning streak. Possible bad omen: He arrives at the premiere with a hooker attached to his limo.

That hooker turns out to be Wendy Ward, played by the mesmerizing Illeana Douglas, an actress with the come-hitheriest eyes this side of the Mona Lisa. Today a hooker, tomorrow a studio executive; it turns out that Wendy knows as much about what makes a hit movie as almost any of Dragon's other underlings. She is soon in his employ, performing duties other than those she's used to.

Real names, like Robert Downey Jr., Bruce Willis and O.J. Simpson, are dropped into the script at regular intervals. Real stars like Keanu Reeves show up for self-effacing cameos. And one scary character seems clearly based on real-life bald mogul Barry Diller, one of the founding fathers of Fox TV, who now runs Studios USA.

Buddy Hackett is present but underutilized as Dragon's uncle, chauffeur and culinary counselor. "Seinfeld" fans will recognize Jarrad Paul, who so winningly played Kramer's intern, now cast in the role of a novice writer named Adam Rafkin whom Dragon keeps confusing with Alan Rifkin.

On the day after the "Slow Torture" premiere, Dragon and company attend what looks like a gay Christmas beach party in Malibu. Here the show reaches dangerous heights of irreverence, using Christmas songs as counterpoint or comment on "Action's" action. The piece de resistance, so to speak, is when Dragon gets a look at the enormous endowment of a studio boss as he steps from the shower. On the soundtrack: "Do You See What I See?"

"Action" is one of those rare shows that click and crackle from the first moment on. But there's a caveat. Critics are likely to be fonder of the show than the public; viewers may justifiably not give a hoot about the insider references and may not want to welcome "Action's" collection of shady schemers and ruthless rotters into their homes each week. They're despicable, yes, but like nests of snakes or swarms of scorpions, they effortlessly command attention.

Indeed, it's hard to take your eyes, and ears, off them.

CAPTION: Comic Jay Mohr as the greedy movie producer Peter Dragon.

CAPTION: Illeana Douglas as Wendy Ward, a hooker turned studio exec.