HOTSHOT TV animators used to knock on Disney Channel’s door very infrequently. For a generation of cartoonists raised on “The Simpsons,” Disney had a reputation as too worried about protecting its brand to have fun. The cool kids wanted to work elsewhere.

How the cartoon tides turn. Disney hired some daring young managers — notably Mike Moon, known for Cartoon Network’s “Foster’s Home for Imaginary Friends” — and took a chance on a silly show everyone else turned down: “Phineas and Ferb.” It became a smash hit, and the Disney Channel was in the game.

Which brings us to Alex Hirsch, 27. As a student at the California Institute of the Arts, he was talented enough to get noticed by Jeffrey Katzenberg, the chief executive of DreamWorks Animation. (“He called me during class and was, like, ‘Hey, buddy!’ ” Mr. Hirsch said.) But Mr. Hirsch couldn’t be swayed: He wanted to work for Disney’s TV shop.

The result is Mr. Hirsch’s spooky and flatly bizarre “Gravity Falls,” which arrived on Disney Channel in June and is already a ratings success. Twins Dipper and Mabel go to Oregon to live with Grunkle Stan, a hairy-shouldered relative who sits around in boxer shorts and a Shriners hat. Dipper wants chest hair; Mabel adores arts and crafts. Co-starring are gnomes; Bigfoot; a multi-headed bear; Tyler the Cute Biker; and Lazy Susan, a one-eyed waitress.