NEW YORK — Much has been written about American superheroes like Spider-Man and Batman being portrayed in movies by Brits, but the greater growth in outsourcing of talent is in television. Indeed, more than a dozen broadcast network pilots this year feature emigres in major roles, including “Appelbaum,” “Cult,” “666 Park Avenue,” “Scruples,” “Golden Boy” and “Beauty and the Beast.” Industry experts say the number of imported performers has been growing steadily — and the pace is accelerating.

“You can track the progress around the globe over the past decade,” says casting director Linda Lowy, who cast Sarah Bolger of Ireland and John Barrowman of Scotland in the ABC pilot “Gilded Lilys.” “First there were more Canadians, then English and Irish actors, and now Australians and New Zealanders.”

And this year, Lowy observes, the phenomenon has seemed more pronounced than ever. “I had one casting session where Americans were in the minority,” she says. “These changes are here to stay.”

A driving force behind the trend is technology that allows actors around the world to self-record high-quality auditions in formats that can easily be shipped and played anywhere. Eric Dawson, co-founder of casting company Ulrich/Dawson/Kritzer, who placed English actors Gina Bramhill and Al Weaver in the pilot for the NBC period drama “Frontier,” illustrates how the trend has grown in just the past year: For FX’s 2011 pilot for “American Horror Story,” he says, he had about 75 self-recorded auditions from around the English-speaking world; for “Frontier” he had more than 300.

Some say such oncamera auditions are a better barometer of an actor’s abilities on TV, while others say something is lost by not being able to respond to in-theater direction, particularly regarding the give-and-take of comedy. Still, there’s no disputing the growing mountain of pre-recorded tests.

“Actors are getting so used to doing it this way that the studios in England and Australia where they shoot (these auditions) are getting backed up,” Dawson says.

Seizing the chance to find fresh faces, studios and networks have hired casting proxys in the U.K., Australia, Vancouver and Toronto to scour for new talent, says Beth Klein, senior vice president of casting at Universal Television, which saw NBC pick up pilot “Animal Practice” featuring Canadian thesp Tyler Labine and Irish actress Amy Huberman.

And casting director Lynn Kressel, who placed actors Aussie Jesse Spencer and Brit Eamonn Walker in “Chicago Fire,” says that as producers and studio execs hire more international thesps, casting directors are encouraged to pursue overseas talent.

One positive is that with pilot season becoming more crowded as more networks rely on original shows to boost their brands, the influx of thesps means shows are less likely to be competing for the same actors.

However, there are drawbacks. Lowy says that networks and studios are putting so many people on tape, “often without any direction,” that casting directors have more and more auditions to wade through in a short time. Worse, permit problems can cost a production time and money. Lowy says that unless foreign actors end up living in the States, the time needed to clear them for visas prevents them from doing episodic work.

According to SAG-Aftra, actors who are hired to perform in productions produced under its jurisdiction become members of the guild in the same manner as locally hired performers, in the event they’re not already members. “We don’t control who the producers cast or hire for their programs and we are always extremely pleased to see more jobs for SAG-Aftra members,” says a guild spokeswoman.

Still, talent agencies are trying to capitalize by signing more and more foreign actors.

“I think sometimes they’re signing them sight unseen and holding onto them just through the pilot season,” Lowy says. “If they don’t get a series, they get cut loose. But meanwhile we get a call from each agent.”

One of the things casting directors have discovered is that foreign actors’ American accents have been improving. And Klein observes that increased training has produced more nuanced regional accents.

“They’ve realized they have to get it down, or they can’t come over here,” Dawson says.