A former exec for Cartoon Network, which includes programs like “Aqua Teen Hunger Force,” will create animated shows for Fox. (TURNER BROADCASTING SYSTEM)

“Primetime animation has been an enormous part of our legacy,” Reilly said. Meanwhile, “we have real estate, it occurred to us, on our schedule in Saturday night late night that we have not been programming now for quite a few seasons. And it occurred to us that that was an opportunity that we were giving up, that we could take some of that [animation] talent that we want to be in business with, we could take some of that product, and we could program it on Saturday night.

Fox plans to launch the late-night programming block a year from now, on Saturday nights from 11 p.m. to 12:30 a.m.

A digital channel, extending across such platforms as Web, mobile apps, game consoles and video on demand, will kick off this year, featuring 50 original short-form pieces per year.

Fox has hired Nick Weidenfeld to run the operation. Over the last eight years, Weidenfeld helped grow the late-night block of programming on Cartoon Network known as Adult Swim into the No. 1 rated cable entertainment channel among young guy viewers, with animated programs that include “Aqua Teen Hunger Force” and “Robot Chicken.”