• Bob D'Amico/ABC / The Denver Post

    ABC's "Marvel's Agents of S.H.I.E.L.D." is a spinoff from "The Avengers" movies,

  • Robert Voets / CBS

    Melissa Benoist stars in the new CBS series "Supergirl."



‘Supergirl,” probably the most-talked about new show of the fall, arrives on CBS on Monday. And when she gets here, that will put all of the big broadcast networks in the comic-book business.

ABC delivers “Marvel’s Agents of S.H.I.E.L.D.,” a series that is a spinoff from “The Avengers” movies, and its summer counterpart, “Marvel’s Agent Carter.” Fox counters with “Gotham,” a prequel story to the Batman saga. NBC offers its homegrown superstory, “Heroes: Reborn.”

The CW serves up two interconnected superhero shows, “Arrow” and “Flash,” and is developing a third, “The Atom.”

And that’s not counting two series based on comic books sans superpowers, the CW’s “iZombie” and the 600-pound gorilla of Sunday nights, “The Walking Dead.”

This is not the first time we’ve seen superheroes in primetime. Over the years, we’ve seen Superman and Batman, Spider-Man and the Hulk, Wonder Woman and an earlier version of the Flash. But those tended to be rare and perform poorly. How did a genre with such a spotty track record suddenly grow to dominate the network schedule?

There are a number of factors.

Foremost is the integration of formerly independent comic-book companies into entertainment conglomerates. The two major publishers, Marvel (Spider-Man, the Avengers) and DC (Batman, Superman) are now owned by Disney and Time Warner, respectively. Disney owns ABC and its TV production arm, while Time Warner owns the Warner Bros. Television studio and half of the CW.

Technology plays a role, too. Computer-generated graphics have made movie-quality special effects available on a television-production budget. And thanks to high-definition broadcasts, viewers can appreciate those effects.

Part of the comic-book trend is simply TV’s copycat nature, where a little bit of success breeds a lot of imitation. In the late 1950s, Westerns dominated primetime; today, they barely exist. The late 1990s was the golden age of sitcoms. And it wasn’t too long ago that “Grey’s Anatomy” and “Desperate Housewives” sent network executives on a soap-opera spree.

Comic book series, too, have found a new maturity, focusing on characters and their struggle to come to terms with their powers – and less on the powers themselves.

“Smallville,” the series about Superboy that ran for 10 years on what is now the CW, gets the credit as the archetype. Successful superhero movies usually built their first act around the character’s “origin story.” With “Smallville,” the origin story was the entire story.

Since then, nearly all superhero series are about the protagonist learning to be a hero.

Greg Berlanti, executive producer of “Supergirl,” “Arrow” and “Flash,” told a group of television critics recently that special effects and fight scenes work best when they are secondary.

“In terms of the superpowers and action set pieces, for me, they’re … worth spending all that money on when they really demonstrate something about the person’s character,” Berlanti said. “So whether it’s the emotional thing they’re kind of struggling with in that episode or whatever it is they have to kind of overcome, so that’s where we try and stay focused on the character.”

In “Supergirl,” this takes the form of a 24-year-old woman struggling to launch her career who finds a personal awakening through her superpowers. In contrast with the darker, more brooding “Arrow” and “Flash,” “Supergirl” is a brightly lit ode to empowerment – one that owes a debt to director Richard Donner’s “Superman” films of the 1970s and ’80s.

“I grew up really worshiping the Donner films and their magic and their wonder and their joy and their fun,” Berlanti said. “When we went in last year to talk to Warner Bros. and DC and they mentioned the possibility of us working on a show like ‘Supergirl,’ our real hope was to bring just a smidgeon of that magic that those films had.”

That puts much of the onus for the show’s success on its star, Melissa Benoist, a 27-year-old actress previously known best for her work as Marly Rose on a season of “Glee.”

Despite her lack of name recognition, the show’s producers are high on Benoist.

“She was the first person we saw,” executive producer Ali Adler said, “and we looked at each other and were blown away, and we were like, ‘We have to get a diamond ring for that girl.'”