AMC's "Mad Men" will return Sunday, March 25. (Mike Yarish/AMC)

That long-delayed “Mad Men” will debut its fifth season with a two-hour episode on Sunday, March 25, the network’s programming chief Joel Stillerman revealed to a hotel ballroom’s worth of critics.

And, “The Killing” returns for a second season with a two-hour premiere on Sunday, April 1. But, Stillerman hastened to add, despite the state of high knicker-knottedness among some of the TV critics, the killer from Season 1 will not – repeat NOT -- be revealed until the end of Season 2. Which, he noted, is how it played out in the series’ original, Danish version.

“We want you to know we learned a lot from your response to Season 1…we heard you clearly,” Stillerman told petulant critics, obsequiously, in re their outrage over the Season 1 finale non-killer-revealing cliffhanger.

We learned a lot too. We learned that not all TV critics do enough homework, like re-read their own TCA Press Tour transcripts from last January’s press tour, in which show developer Veena Sud told the critics there was no guarantee the killer in the first-season storyline would be revealed by the end of that season.

“I can confirm the killer will be revealed in the Season 2 finale,” Stillerman told a hotel ballroom’s worth of TV critics attending the tour one year later. “Be nice!” he said when some members of the mob began to snarl.

Stillerman said AMC execs actually looked at the option of veering away from the original Danish drama series, in order to reveal the killer sooner, but realized it would be like pulling the thread on a sweater.

And so the network decided — but only after “significant discussion” he assured the critics — “to do justice to the story” they “fell in love with, resolving the murder at the end of Season 2.”

The mob began to suck on that happily.

Getting back to Stillerman’s announcements:

AMC’s zombie drama “The Walking Dead” returns on Feb. 12 – the same night the network premieres its new six-episode reality series “Comic Book Men.”

Kevin Smith (“Clerks,” “Chasing Amy”) is among the exec producers of the show, which is set in his comic shop.

The “Mad Men” debut date announcement puts the finishing touch on a months-long saga that began in late March of ‘11, when AMC announced it had triggered its option with production company Lionsgate to telecast a fifth season of the tony period drama. At that time, AMC said the fifth season would not be ready in time for a summer ’11 debut — the play pattern for the first four seasons.

AMC said at that time it would have to delay the show’s return until some time in early 2012 because of a contract dispute with show creator Matthew Weiner, whose contract ended at the end of the fourth season.

Weiner’s new contract was being held up because he was not happy with plans to slice a couple minutes off each episode in order to add commercial time, to cut cast in order to cut costs, and to beef up product placement in the already pretty product-placed show.

There was also a raging debate as to whether AMC would get to allow advertisers to advertise their advertisements on the show. That was kind of a hilarious point of contention, given that “Mad Men” is a drama about the epicenter of crass American commercialism — Madison Avenue — in the ‘60s.

Anyway, few days later, Lionsgate and AMC ended their game of high stakes chicken with Weiner and sealed a deal for him to continue to helm the show for three more seasons. And they all lived happily ever after.