Who says cartoons are for kids? Family Guy and American Dad creator Seth MacFarlane tops Entertainment Weekly's list of the 25 smartest people in television.

The magazine says Family Guy DVDs and merchandise have earned a reported $US1 billion ($A1.55 billion). MacFarlane is the highest-paid writer in TV, with a Family Guy spinoff called The Cleveland Show in the works.

"That frat-boy persona is only a cover," says Entertainment Weekly.

30 Rock creator and Sarah Palin imitator Tina Fey is second on the magazine's list. CBS Paramount Network Entertainment chief Nancy Tellem is third. Oprah Winfrey came in sixth.