On Saturday afternoon, Fontana debuted a new episode of the cartoon for an excited crowd at the FanX convention in Salt Lake City.
"We really are committed to bringing an epic action series to girls," Fontana said. "We know that there are girls who are fans out there, and we've been ignored as women a lot in the comic book industry. And we are finally breaking through, and making this series just for you."
In the new episode, a teenage Wonder Woman invites Supergirl to join her and others like her at Super Hero High. In this fictional universe, DC Comics' heroes and villains alike are teens attending the same school, learning how to use their powers to save the world.
Supergirl is unsure of herself, but Wonder Woman believes in her.
The warrior princess' encouraging words come from veteran voice actress Grey DeLisle, who gives Wonder Woman her inner strength.
"Just because she's young doesn't mean she's not strong," DeLisle said. Wonder Woman is surrounded by other empowered girls like Bumblebee, Poison Ivy, Harley Quinn, Katana and Batgirl.
"These girls have all really got this boldness and go out and take action on things, and I think that's a really important quality," Fontana said. "… They don't have to be the romantic interest. They're not just the girlfriend or the wife in the script. They're really at the center of the story."
Their world is growing, too. Besides the cartoon, an hour-long special debuted last week on Boomerang, and Fontana teased that it's coming to other channels, as well. Random House published a "Wonder Woman" middle-grade novel earlier this month with plans for several more.
In the leadup to the book's release, its author Lisa Yee told The Salt Lake Tribune that she didn't understand "why this didn't happen a long time ago, but I'm so glad that it's happening now and that I'm able to be a part of it."
Fontana's also written two upcoming graphic novels, with a preview coming out on the annual Free Comic Book Day (May 7).
And earlier this year, Mattel released a line of action figures which have sold so well, Fontana said they were sold out at the Target stores in Los Angeles, her new home. But after pulling strings with the toy company, Fontana brought six of them to FanX to give away to girls in the audience.
She gave a Poison Ivy action figure to a young girl who wondered whether they'll make a "DC Super Hero Girls" movie. Fontana couldn't release any specifics.
But she did pass along an empowered, female superhero to a young fan. And when she and DeLisle are back in LA, they'll keep doing just that for millions more.