TORONTO - Zach Galifianakis appreciates the fact that he's a big, cuddly clown, but he also knows there's more to him.
Ask Toronto actor Keir Gilchrist, who stars opposite Galifianakis in It's Kind of a Funny Story, which premieres at the Toronto International Film Festival this weekend and opens in selected theatres Oct. 8.
Galifianakis has gone to great lengths to prove his versatility this year, so the comic actor hopes audiences will be paying attention.
Certainly, Funny Story headliner Gilchrist, who's been making a name for himself as the fey son Marshall in the cable series, The United States of Tara, was impressed with the transition.
Since establishing himself as the weirdo, tagalong brother-in-law in the R-rated romp The Hangover, Galifianakis has been trying to challenging himself any way he can.
This summer, he had some scene-stealing moments as the mind-bending mentalist Therman in Dinner for Schmucks with Steve Carell and Paul Rudd.
In Due Date, out in November, the 40-year-old reunites with Hangover director Todd Phillips for a road-trip comedy. Galifianakis portrays a high-maintenance actor who offers to drive an anxious father (Robert Downey Jr.) across the country to make the birth of his daughter.
Both of those roles seem to be in his comfort zone: playing the oddball for laughs.
As a variation on the theme, Galifianakis goes for more depth in It's Kind of a Funny Story - "and I am very pleased with the results," said the affable comedic actor at a downtown hotel.
Based on the Ned Vizzini teen novel, the film features Galifianakis as Bobby, a suicidal psychiatric hospital patient who befriends Craig (Gilchrist), a teen from an upper-middle-class Brooklyn family admitted for depression.
When the 16-year-old first arrives at the mental-health wing of the New York hospital, he's anxious and unsure, stressed out over his love life and the pressure from making the grade at his "executive pre-professional high school".
As Galifianakis's Bobby tries to show him the ropes at the facility, they learn from each other in very different ways.
Also in the mix is Emma Roberts, Julia Roberts's niece. She plays a seemingly confident teen patient coping with her inner demons. Oscar nominee (for Doubt) Viola Davis plays the straightforward ward psychiatrist.
And while it's the troubled teen who innocently narrates the movie, It's Kind of a Funny Story tackles some mature themes.
Galifianakis gives a great deal of the credit to the writers and directors, Anna Boden and Ryan Fleck, who also worked on Half Nelson (which earned Ryan Gosling an Oscar nod) and Sugar.
Still, as he walks a fine line between funny and sad, it is Galifianakis who shines, offering his most complex performance yet.
"I knew going into it that I didn't want to stand out like a sore thumb and be too wacky with the portrayal," he said. "I also appreciated the fact that I was there to service the main story, but the directors were pretty good at figuring that out for me."
"And really, I prefer movies that are more grounded," he said, "so they (the directors) didn't have to rein me in."
To establish his character, he also researched mental illness, and spoke with some patients.
"I talked with a couple of people who looked like they could function in real life, but they had problems, and they showed it with sadness and anger in their eyes, and I tried to use that with Bobby."
What he won't take credit for is the undeniable connection between his character and Gilchrist's troubled teen. "That's all because of Anne (Boden) and Ryan (Fleck)," he said, referring to the writer-director team. "I think they had really thought through the casting, and we got lucky that it seems so organic."
Meanwhile, Galifianakis reunites with his Hangover buddies - director Phillips and castmates Bradley Cooper, Ed Helms and Justin Bartha - for a squeal to The Hangover, which starts shooting in three weeks for release next summer.
Is there pressure to match the critical and box-office success of the first Hangover? "Absolutely, there is no denying it," noted Galifianakis. "It's sort of a risky thing to do, but we all trust each other."
He'll also voice Humpty Dumpty in the Shrek spinoff, Puss in Boots, out next year, as well.
"I know," he said smiling, "even in animation, I'm playing something fat. But it was a lot of fun to do the voice work, and a challenge to be alone in the abyss of a recording studio, and try to make something work over and over again."
So, no worries. His comedy fans won't have to adjust. He's not abandoning them for more serious projects, but there's no question that It's Kind of a Funny Story will allow him to consider more and varied opportunities.
"To me, it's all about doing different things," he said. "I don't sit around and think about it that much. Doing standup is the way I live my life, but I would love to do more dramatic things, because it's so much easier to be solemn than it is trying to get a laugh."