There’s just no killing the zombies of AMC’s “The Walking Dead,” as the mega-hit returned Sunday to open its fifth season with more record-setting ratings.

Nielsen estimates that an average audience of 17.3 million watched Sunday’s premiere, besting the show’s previous high — 16.11 million for its fourth-season premiere a year ago — by more than 1 million.

It also crushed the show’s record in adults 18-49, with Sunday’s 8.7 rating (roughly 11 million viewers in this age range) easily topping the 8.2 it had earned with both its premiere and mid-season return last season. “Walking Dead” easily bested NBC’s “Sunday Night Football” game between the New York Giants and Philadelphia Eagles (roughly 6.7), which was a lopsided affair.

This is easily the top “live plus same-day” demo rating for an entertainment telecast this season — well above the 5.5 earned by the season premiere of CBS’ “The Big Bang Theory.” And among all primetime programs, it ties at No. 1 with the Sept. 28 “Sunday Night Football” game on NBC between the New Orleans Saints and Dallas Cowboys.

“Walking Dead” has become a monster in total viewers, as well. Among entertainment series, Sunday’s premiere total is competitive with a trio of CBS shows from premiere week (“The Big Bang Theory” and “NCIS,” which both topped 18 million) and newcomer “NCIS: New Orleans,” which bagged 17.2 million in “live plus same-day” results.

Three years ago, “Walking Dead” kicked off its second season with a 3.8 demo rating and 7.26 million viewers overall, only to spike with each of its next two premieres: a 5.8 in the demo and 10.87 million in 2012 and then to an 8.2 and 16.11 million a year ago.

AMC projects that with a full week’s of time-shifted viewing included, “Walking Dead” could hit 22 million viewers.

Following the season premiere of “The Walking Dead,” AMC scored with the return of post-show “Talking Dead,” which drew a 3.5 rating in 18-49 and 6.9 million viewers overall.