Superhero epic The Avengers, among this year's most buzzed-about films, blasts into North American theatres this week bolstered by boffo box office results overseas.

Word-of-mouth reviews have been strong from those who attended advanced screenings, while the star-studded film racked up $178.4 million US this past weekend in the 39 countries where it has been released.

Toronto hosts the Canadian premiere of The Avengers on Monday, with cast members Mark Ruffalo (playing Bruce Banner/The Hulk) and Cobie Smulders (S.H.I.E.L.D. Agent Maria Hill) in town for the red-carpet debut.

"It's a nice change for me, an unexpected one," Ruffalo, who typically appears in dramas and independent films like the Oscar-nominated The Kids Are Alright, told CBC News on Monday.

The Avengers co-stars Cobie Smulders, left, and Mark Ruffalo stopped into Toronto on Monday for the film's Canadian opening. (CBC)

"I don't think one [type of film] cancels out the other, for some reason. There's an audience for this, of course, and obviously a huge audience... but little movies like The Kids Are Alright, which — you know — should probably never have been able to get made, gets made. And people love it and they watch it and champion it."

Vancouver-born Smulders, best known for the hit TV ensemble sitcom How I Met Your Mother, agreed that participating in a range of films is valuable for performers.

"It's also to the benefit of the actors to be in a movie like this and to be seen by a different audience and then go on to do your own film, or join onto another independent film, and bring some of this audience to those movies," she said.

Even in a massive, action-packed production like The Avengers, which combines several existing Marvel superhero movie franchises, there are moments for the stars to stretch themselves as actors, the duo said. Regardless of the film's size, the two co-stars also agreed it was important to be honest to the character.

"[Director] Joss Whedon did such an amazing job with the script where, yeah, there are these huge action sequences and you're asked to be tough and you're asked to be strong. But there are also these great emotional scenes in this film, or scenes where there are two of these superheroes interacting, having a conversation. And that's so interesting to see as well," Smulders said.

"At the end of the day, you have to be honest to your character — and if your character is big and brash, then that's what you be," Ruffalo said.

The Avengers, also starring Robert Downey Jr., Chris Evans, Scarlett Johansson, Chris Hemsworth, Jeremy Renner and Samuel L. Jackson, opens theatrically in North America on Friday.