“World’s Greatest Dad,” which was written and directed by comedian Bobcat Goldthwait, was one of those small movies from 2009 which got released under the radar. It does star the late Robin Williams, but it never got the same level of marketing some of his others got that year, namely “Night at the Museum: Battle of the Smithsonian” and the god awful “Old Dogs.” But those who have a deep love for twisted humor should enjoy this one, and it features one Williams’ last great performances before he prematurely left the land of the living.

Along with Jody Hill’s “Observe and Report,” 2009 was quite a year for black comedies which managed to mine comedy out of the most sensitive of subjects. Williams plays Lance Clayton, a failed writer and poetry teacher who is the antithesis to Mr. Keating from “Dead Poet’s Society.” The class he teaches is not at all popular, and he is unable to inspire his students or make them seize the day. Lance dreams of publishing one of his novels and of becoming rich and successful, but this success has eluded him throughout his life. Of course, once you look at the kind of novels he writes, it becomes sadly understandable why he has received a truckload of rejection letters.

Lance is also a single father to his son Kyle, a kid who many would go out of their way to nickname the antichrist. Has there ever been a ruder, endlessly selfish, thoughtless, or verbally abusive son in the history of cinema? I’m sure there are, but none come to mind at the moment. Kyle makes Rhoda Penmark from “The Bad Seed” look like Teddy Ruxpin, and he’s what Macaulay Culkin’s character from “The Good Son” would have been like if the filmmakers weren’t subjected to the iron grip of Kit Culkin. Maybe these are extreme comparisons, but they seem to fit.

Then one day, Lance comes home to find his son Kyle dead in front of his computer after accidently strangling himself during the act of autoerotic asphyxiation. Knowing the way he died, once revealed to the public, will be humiliating for him and forever put a stain (no pun intended) on his son’s memory, Lance makes Kyle’s death look like a suicide and even writes a suicide which ends up having more emotional depth than anything which could possibly have come out of Kyle’s shallow little mind. Once the note is made public on a police website, everyone at school starts seeing Kyle in a different, albeit completely false, light, and Lance soon gets the fame and adoration he always dreamed of having, and this leads him to pen a fake memoir in his son’s name.

From this description, “World’s Greatest Dad” looks to travel down the same satirical roads as “Heathers” in how it depicts the absurd effect a person’s death can have on us, especially when it involves someone we hardly knew or truly despised. But as familiar as these roads are, the timing worked to this movie’s advantage as it was released not long after the death of Michael Jackson. With his sudden passing, all the crimes he was accused to have committed, but was never convicted of, quickly seemed to disappear as if they were all a fiction, and all we could think about was the great music and dance moves he left us. With Kyle, his sins seem to be miraculously absolved upon his death, and people look to his spirit as if he was some kind of cult hero. It’s all further proof of how we have tremendous respect for the dead, but none for the living, and this saying is amped up to such a crazy degree by Goldthwait.

But Goldthwait also has an even bigger target than our adulation for the not so dearly departed, and that’s the hollow pursuit of fame. We all know this filmmaker best from his days as a comedian, and his off-kilter voice had us laughing endlessly time after time. Seeing his work as a filmmaker should make you realize there is more to him than his talent for burning up furniture on “The Tonight Show.” Being as famous as he is, Goldthwait understands how fame can bring you in touch more with people who don’t have your best interests at heart as well as others who never have cared about you in the first place. It becomes easier to see why having all this adoration can make you feel even more than you ever have before.

Kyle’s death ends up turning just about everyone at school into an utter hypocrite. Many who would rather have beaten the leaving crap out of him suddenly come forth to say they were actually friends of his. Even the principal and school psychologist try to use Lance’s new-found fame to advance their career goals. Heck, a Goth chick becomes a Bruce Hornsby fan after Lance tells her Kyle was as well. Of course, we have already previously seen how Kyle hated Bruce Hornsby as much as Lance loved to listen to him, and the level of absurdity reaches epic heights once Lance publishes his son’s fake memoir, and the book deal which has long eluded him suddenly becomes a reality.

Williams’ performance in “World’s Greatest Dad” showed how great and subtle he was to where it wasn’t always necessary for him to act crazy 24/7. Aside from his concert tours, seeing him going all nuts in a movie eventually wore out its welcome, and at times it felt like he was desperate to make us laugh. But as Lance Clayton, Williams never overdoes anything, and he makes the character sympathetic even when we know what he is doing is very wrong.

Williams also captures the lonely life of an unpublished writer whose existence is filled to rim with endless rejection. Seeing another teacher getting an article published in the New Yorker, and on his very first try by the way, brings about a resentment in him he can’t quite hide. The “Good Will Hunting” actor captures Lance’s pain perfectly, and he grounds this character in a reality which grows increasingly bizarre as the movie goes on to where he never has to a single scene just for laughs.

But one actor who truly deserves a lot of credit is Daryl Sabara who plays Kyle. Perhaps best known for his work in “Spy Kids,” Sabara doesn’t even try to find any redeeming qualities in this astonishingly vulgar character because it feels like there are none to find. Building on the school bully he played in Rob Zombie’s “Halloween,” he fearlessly makes Kyle one of the most despicable teenage characters I have ever seen in motion pictures, and he even makes Danny Lawrence from “The Karate Kid” look like a real pushover. Sabara’s work here is fearless, and you have to give him big props for how far he was willing to go.

I also really liked the lovely Alexie Gilmore as Claire, the younger teacher who is more or less dating Lance while having eyes for another teacher, Mike (Henry Simmons from “NYPD Blue”). Her adorable personality and warm smiles make you almost completely forget how incredibly self-serving she is. Perhaps Claire doesn’t even know how selfish she is as she remains very coy about her relationship with Lance, but we cannot look past how selfish she is in her own desires. Despite all this, Gilmore still makes you root for her to be with Lance even after we realize this relationship is not in Lance’s best interest.

Many have complained about how “World’s Greatest Dad” ends with a number of issues unresolved, and this is true. Things are tied up a little too neatly, and you get the impression Goldthwait could have made this black comedy even blacker than it already is. Still, he shows a lot of guts taking on such touchy subject matter which other filmmakers would never dare deal with. As dark a comedy as this may seem, he also makes it a very moving one. Once you get past what you see on the surface, there’s actually quite a bit to take in. With this film, Goldthwait makes us understand how being alone can be nowhere as bad as being surrounded by people who make you feel lonelier than ever. Remember when Travis Bickle talked about being “God’s lonely man?” Well, I was reminded of that here.

Goldthwait previously directed several films before this one including “Shakes the Clown” and “Sleeping Dogs Lie,” and he would later give us an even darker and more biting black comedy with “God Bless America.” But aside from working in comedy, he also directed the found-footage horror movie “Willow Creek,” and he gave us one of the most unforgettable documentaries of recent years with “Call Me Lucky” about the late comedian Barry Crimmins. Like “World’s Greatest Dad,” they deserve a bigger audience than they have received to date, and they demonstrate how talented Goldthwait is behind the camera as well as in front of it.

Williams and Goldthwait were great friends off screen, and their appreciation for one another really showed here. “World’s Greatest Dad” may seem like an unusual movie to view on the very important occasion of Father’s Day, but you can only watch Gregory Pick in “To Kill a Mockingbird” so many times. Lance Clayton may not be the greatest dad as the title infers, but you never doubt the love he lies about him to the world to achieve fame and cover up what an infinite little prick he was in his short life. For those in the mood for a thoughtful black comedy, this one delivers.

Besides, is there any other movie out there featuring two teenage girls getting in a catfight over a Bruce Hornsby CD?

* * * ½ out of * * * *