They wouldn't have known what to do with Toni Collette in Golden Age Hollywood. Back in the day when movie stars' personas were cultivated like hothouse flowers, the last thing a studio wanted was a star who was entirely different from one picture to the next, who took equally well to comedies, dramas and everything in between, and who vanished into her parts, leaving not a trace of star persona.

But that's Collette: The Australian actress has an enviable string of hits to her name, including Muriel's Wedding, The Sixth Sense, About a Boy, The Hours and In Her Shoes, but so uncanny is her ability to step into the skin of a character that people often fail to recognize her from one film to another. Case in point: Two very different new movies, both starring Collette, 33. In the offbeat comedy Little Miss Sunshine (scheduled to open Aug. 18) she plays Sheryl Hoover, a harried wife and mother trying to hold together a dysfunctional family that includes her judgmental husband (Greg Kinnear), her gay, suicidal brother (Steve Carell), her foul-mouthed father-in-law (Alan Arkin), her angry son (Paul Dano) and her chubby, precocious, seven-year-old daughter (Abigail Breslin) -- whose entry into a prepubescent beauty pageant snares the whole family in a wild, unpredictable road trip.

The movie earned rave reviews at the Sundance Film Festival, and is shaping up as a cult favourite. The Night Listener, (scheduled to open Friday), is a different story, and stars a very different Collette. It's a thriller, based on a novel by Armistead Maupin, in which she plays Donna, a dark and disturbed woman whose adopted son, a troubled 14-year-old, strikes up a long-distance friendship with a late-night radio host (Robin Williams). It's when the host decides to meet the boy in person that things start to get creepy. "I'm really thankful to have the chance to play all those parts," she says. "These two movies are both so great and different. I can't imagine doing it in any other way. If I wanted to do the same thing over and over again, I'd probably do a sitcom."

Collette may be a Hollywood favourite nowadays, but home is still Australia -- specifically Bondi Beach in Sydney, where she shares a home with her husband of three years, drummer Dave Galafassi. "I've never had any master plan about taking roles," she says. "It's almost like the roles chose me. There's never any rhyme or reason, other than that I love what I do and I want to keep doing it.

"In Sunshine Cheryl is the glue that holds this family together," Collette says, her azure-blue eyes suddenly coming alive. "She's selfless, incredibly supportive and patient. She'd die for any member of her family. She encourages them to be who they are, and she's not like her husband, who puts pressure on everyone to be a winner and be something that's unobtainable. "Mind you," the actress adds with a smile, "that's pretty similar to what society does to all women." It's harder to describe her mysterious Night Listener character without giving away key plot surprises, but Collette does her best. "Donna is a complex and layered person, someone who has had a really hard life. We all want love, and not all of us are lucky to get it. She's probably been abused in the past. She's really intelligent, but she uses her smarts in a destructive, manipulative and frightening way."

Between The Night Listener and Little Miss Sunshine, Collette went off to Thailand to join the ensemble cast of the HBO miniseries Tsunami: The Aftermath, set to air in December. She plays an Australian missionary teacher caught up in the aftermath of the deadly Indian Ocean tsunami of December 2004. "Some people may think it's too early for a film about the tsunami, (and) it may be too early for the survivors, but it's not too early to tell their story for the rest of the world." Although her workload is still a heavy one, Collette insists she has become choosier about the roles she takes.

"In my 20s I worked so much, but now I prefer to have a really stable, normal life. Not long ago I suddenly realized that this career that I've somehow managed to get is not going away. I have another life with my husband, and now we're thinking about starting a family."