The maxim of writing what you know certainly applies in Hollywood, where it’s possible that more film has been spent on navel-gazing than covering Oscar bait like terminal illness and period dramas combined.

But most writers and directors in Hollywood have enough sense to realize that acting is not rocket science. The portrayal of the subject in film seems to be nearly entirely a matter of revenge. Comedy is a genre well designed for writers and directors to take out their frustrations on spoiled, self-obsessed actors, while drama serves as an outlet for television and film stars to express their admiration for the low paying but highly regarded work of the stage.

More films than can be counted have livened up their plotlines with a sprinkling of overpaid, shallow stars (Thomas Haden Church in “Sideways,” Meryl Streep in “Postcards From the Edge”), innocent, or seemingly so, ingenues (most any young blond female playing an actor, though Naomi Watts did more than her share in “Mulholland Drive,” “King Kong,” and “Ellie Parker”), aging stars trying to cope with real life (Bill Murray in “Lost in Translation,” Sam Shepard in “Don’t Come Knocking”), or beautiful but shallow females in the business (Scarlett Johansson in “Match Point,” Charlize Theron in “Celebrity”). And to drive the point home, the deadly business of acting has been made literal in such films as “The Black Dahlia,” “8 mm,” and “L.A. Confidential,” to name a few.

More than a few parodies have taken on the industry to varied degrees of success. John Travolta brought the mob to Hollywood in “Get Shorty,” while David Mamet addressed the insensitivity of Hollywood actors on location shoots in “State and Main,” and Christopher Guest’s usually perfect comedic timing was undone by last year’s awards ceremony satire “For Your Consideration.”

With the ever-present dominance of up-and-coming starlets and heartthrobs within the confines of Hollywood, it is understandable that the men and women who often flounder in the shadow of the onscreen talent (and their overfed egos) might use their pens and camera lenses to take shots at those in front of the camera when it so suits them. Woody Allen spends almost as much time skewering actors on film (“Celebrity,” “Bullets Over Broadway,” “Hannah and Her Sisters”) as he does giving himself the lead and feeding his own ego with unlikely onscreen pairings.

But it is Saturday Night Live alum Steve Martin who has proven especially adept at skewering Tinseltown. “L.A. Story” and “Shopgirl” both captured the idiosyncrasies underlying life in Hollywood, and his underrated Eddie Murphy collaboration “Bowfinger” truly pinpointed the superficiality and hilarity in the shark-infested waters of Hollywood. Among the many perfectly crafted lines Mr. Murphy spews throughout is this gem in reaction to a pun about throwing a guy named Cliff off of a cliff: “It’s too cerebral. We’re trying to make a movie here, not a film.”

In a town known for self-involvement, filmmakers seem to show a rare restraint in taking on their field. But given the right pretense, they are not beyond singing their own praises.

Generally, though, this praise is couched in struggles for another good. In “Stage Beauty,” Clare Danes fought 17th-century sexism. Hagiographies like “The Aviator” permit worship of Hollywood’s Golden Age, and the pursuit of musical glory seems to override any sense of humility on the part of filmmakers and actors (see: “Moulin Rouge,” “High School Musical,” “Fame,” and any other film that comes close to breaking out jazz hands).

But actors are parodying themselves with increasing frequency. Teen stars Topher Grace, Joshua Jackson, and Holly Marie Combs appeared as themselves in “Ocean’s Eleven” and its sequels, while actors often pepper films with cameos and credits as themselves to prove they have a sense of humor.

Perhaps more than any other celebrity, Julia Roberts has made a meta-career playing people who look like her or pretend to be her. In “America’s Sweethearts,” she played the assistant to Catherine Zeta-Jones’s sweetheart, and in “Ocean’s Twelve,” her character, Tess, pretended to be the one and only Julia Roberts. In “Notting Hill,” where she played an American sweetheart who falls for Hugh Grant’s average Joe, she said the following line: “One day not long from now, my looks will go, they will discover I can’t act, and I will become some sad middle-aged woman who looks a bit like someone who was famous for a while.”

Following the arc of her burgeoning career playing people who look a bit like Julia Roberts, that might be a formula for her second Oscar. Along with gaining weight and playing an ugly person, the role of an aging film star can do wonders for an actor’s career. Former silent film star Gloria Swanson redefined her career by playing Norma Desmond in “Sunset Boulevard,” while James Dean and Steve McQueen’s buddy Martin Landau had to wait until 1994 to win an Oscar, for his portrayal of famously overwrought horror star Bella Lugosi in “Ed Wood.”

And perhaps that’s the most appealing part about highlighting the failings and affectations of actors and their profession. Half the battle is just showing up.

mkeane@nysun.com