His manic persona may have ebbed, and his profile may have lowered since the 1980s. All the better for Bobcat Goldthwait, one of the unlikelier Sundance darlings we've run into this year in Park City.

Goldthwait is attending Sundance with the comedy World's Greatest Dad, his second festival entry in four years and a striking, pitch-black collaboration with old pal Robin Williams. The Oscar-winner plays Lance Clayton, a high-school poetry teacher with unrequited literary aspirations and one of the worst sons (portrayed by Daryl Sabara) in contemporary cinema. Similar to Goldthwait's previous film, the underrated, bestiality-tinged romcom Sleeping Dogs Lie, a macabre twist entitles Lance to pursue his life's ambition even as it endangers his job, relationship and pretty much every other facet of his life. Williams cunningly navigates both extremes, charting the outer limits of unconditional love with a cynic's eye and a comic's map, finally discovering himself in the festival's most batshit ending this side of Brooklyn's Finest.

And while we're loath to give much more away, there was no reason we couldn't ask the candid Goldthwait a few other questions about Dad, Williams, Sundance and his aversion to prime-time sellouts:

D: Knowing what we presume about a traditional "Sundance Movie," audiences might be blindsided by a dark comedy like this. How has World's Greatest Dad fit in so far?

BG: I don't know. I'm glad they've taken these last couple movies, but I don’t know where it fits in because I don't think of it that much while I'm making it. It wasn't until I was watching this one for the first time with a crowd that I thought, "Wow. This is really... dark." I know I sound full of shit, but I try not to think about it.

D: This is your second film here in four festivals. What appeals to you about screening here for this audience?

BG: This one's a little different. I think the people who were first showing up to our screenings were just blindly showing up because Robin was attached. Everybody who showed up the last time were people who didn't get into the other movies. That's not my self-loathing; that's just the reality. It's not a big ticket.

D: The logline sells itself, though.

BG: Yeah: "The dude from Police Academy makes a movie about a woman who fellates a dog." But I had this great thing where all these people who like movies showed up and they got past it. They seemed to kind of enjoy it. There was a woman who was trying to walk out, and her friend talked her into [staying]. And then I look over, and my daughter goes, "Look at her now." She was crying about an hour into it. And my daughter goes, "Yeah, you cry, bitch. You cry."

D: But ultimately both films share the themes of people hiding very dark secrets and explore the consequences of keeping those secrets. What about that appeals to you?

BG: I must be terrified about being exposed. Another thing that's similar in my movies is that people are always walking up to the other person and startling them. I'll try not to put that in my next movie. Strangers probably frighten me. But if I keep making movies, I want to make movies that explore these absolutes that don't hold water. Everybody and everything has to bend.

D: And yet these are comedies. What makes those absolutes funny to you?

BG: I think the comedy I'm interested in is the comedy that's awkward. I don't really care about the joke-driven comedies or the gag-driven comedies.

D: It walks a very fine line between humanity and total misanthropy.

BG: Even the characters I kind of have contempt for, I still see them as people. Even the person you might see as the villain in World's Greatest Dad. Kind of by the end of it, I felt bad for him. I feel like he got chumped. He's kind of full of himself, but I'm not sure he needs to be taken down a couple of notches.

D: Robin Williams is an inspired choice for the role of Lance, and it works out as one of the most dynamic roles of his career. How and when did he sign on for this?

BG: Robin's an old, old friend of mine, but I've never really pimped him or exploited him. He always acts like we're peers, which is really weird; it reminds me of Marlon Brando hanging out with Wally Cox. But I didn't write the part with him in mind. I was telling a mutual buddy about it over dinner, and he was like, "What about Robin?" Robin really liked Sleeping Dogs Lie, and he read this, and he said, "I'd like to be in your movie." [Laughs] It's so weird. I even had to rewrite it because the guy I had was younger.

D: What do you think drew him to it?

BG: This character winds up being kind of a hybrid of me and Robin. We even said that at one point when we were making it; we kind of laughed at how we really are.

D: Are your films autobiographical?

BG: Everything I make is usually autobiographical. The stories aren't, but all the people are if you poke around. Sometimes I don't even really know it. In this movie it's funny: There would be someone I don't really care for, and I'd hear them say something asinine. So I just threw it in the script while I was writing it.

D: We were reading your bio accompanying the press notes, which read in part: "As an actor he has appeared in innumerable embarrassing movies and was huge in the '80s. He greatly prefers directing." What is it about your comedy and these "innumerable" embarrassments that you think informed your films?

BG: I do think that all the stuff I went through kind of prepared me for this phase. And really, what's going on my life now — kind of like Lance — I just stopped five or six years ago and said, "You know what? I'm flattered that they're calling from UPN or the WB, but..." The real shame about being a comedian who's well-known is that you don't immediately become a has-been. They just keep dragging you out. Trust me. As soon as Howie Mandel hit pay dirt hosting a game show, I got a million fucking calls to host a game show.

D: Really?

BG: Of course! I mean, Hollywood? "Hmm, who else was an annoying '80s comedian? Oh, Bobcat Goldthwait! Let's get him!"

D: Don’t be so hard on yourself.

BG: But it's the truth. I had this character when I first started; I wasn't even doing stand-up. It was really abstract. And then I got to be a comedian, and I started performing, and I had an act. Now I realize that I stopped being a comedian and became an entertainer, you know? You'd book me in a comedy club in the middle of the country, and my working-class ethics would kick in. I'd do a good show for the people. But I was miserable, man. And I'll still go out and do stand-up. Now I don't mind it, because it affords me the chance to make indie movies. I'm not looking to get discovered. I'm just hoping to keep making these movies that are small and personal.