When “Steven Universe” started on Cartoon Network four years ago, its titular character was a silly, carefree boy (voiced by Zach Callison) singing about the glory of Cookie Cats and his longing to ...

There was a show that Rebecca Sugar used to watch. It was called SWAT Kats and it ran on cable television in the first half of the 1990s. “They were cats, in planes, blowing up stuff,” Sugar says.

When “Steven Universe” started on Cartoon Network four years ago, its titular character was a silly, carefree boy (voiced by Zach Callison) singing about the glory of Cookie Cats and his longing to ...