'The Walking Dead' is TV's most popular drama and its viewership is dominated by young people

"The Walking Dead" rules as television's most popular drama, but the Nielsen company's viewership totals only give a hint at the extent to which zombies rule.

Nielsen said that the AMC show had 13.5 million viewers on Sunday, beating CBS' "Madam Secretary" by one million as the most-watched drama. Yet 8.8 million of those viewers were between 18 and 49 years old, the demographic upon which most television advertising sales are based on.

In that demo, "The Walking Dead" towers over its competition. No other drama had half as many young viewers last week. ABC's "Scandal" was second with 3.7 million.

"The Walking Dead" even beat the NFL's Sunday night game among young viewers for the third time in five tries this week.