Kim Raver and Chris O'Donnell Kim Raver and Chris O'Donnell

It's one of the oldest adages in Hollywood: If at first you do succeed, try and try again... to replicate that hit. Just as the movie business remains entrenched in sequel mania (Scary Movie 5, anyone?), almost every broadcast network has a spinoff of a popular series in the works for next season.

ABC is looking to expand its Once Upon A Time universe with the Alice-centric Once: Wonderland. The CW is building The Originals around The Vampire Diaries baddie Klaus (Joseph Morgan). NBC will explore Chicago law enforcement in producer Dick Wolf's untitled Chicago Fire offshoot.

And CBS has in the works what might be the ultimate brand extension: A spinoff of a spinoff of a spinoff. You may recall that JAG led to NCIS, which spawned NCIS: Los Angeles, which in turn was the incubator last month for NCIS: Red, starring Kim Raver and John Corbett (the characters were featured in a two-part episode).

Insiders at the network say they're looking forward to cross-pollinating NCIS: LA and NCIS: Red — and perhaps even developing a relationship between Raver and NCIS: LA's Chris O'Donnell. When three days of DVR usage is included, the two-part NCIS: LA arc featuring the new Red team averaged 17.7 million viewers, great exposure for a potential new show.

Why are so many spinoffs in the works now? In an age when scores of new shows on broadcast and cable fight for attention, a spinoff comes with built-in audience awareness. Viewers are already familiar with the characters, and the new series are usually similar in tone to that of the shows viewers already love.

In the case of The Originals, Thom Sherman, The CW's executive vice president of development, says the network had been kicking around ideas for a Vampire Diaries spinoff since Season 2, and the timing finally felt right this year. "You want to catch it at a time when creatively the show you're spinning out of is still really strong," he says, "and even continuing to rise."

Sherman and Vampire Diaries executive producer Julie Plec say they're invigorated by the idea of putting a villain at the new series' core. "There's something so wonderfully damaged about [Klaus]," Sherman says. "Something about getting to the heart of his pain and the depths of what that is, which he barely reveals in The Vampire Diaries. The story of The Originals, I'm not sure that anyone knows what is coming."

The Originals pilot will air as an episode of The Vampire Diaries on April 25; the spinoff follows Klaus and his family of vampires as he moves back to New Orleans — a city he helped create centuries ago. Adds Sherman: "It completely sets their world on a completely different axis. It's a whole new mythology. The Originals has to stand on its own."

As More Networks Develop Series, Is There Too Much TV?

Subscribe to TV Guide Magazine now!