'The Walking Dead' may have teased one of the next big villains back in season 3

Warning: If you're not caught up with "The Walking Dead," both the show and the comic series, there are some spoilers ahead.

"The Walking Dead" season five finale is Sunday evening at 9 p.m.

Right now, Rick and his group are living (relatively) safely behind the walls of Alexandria. (Though after last week's episode, Rick may be messing up the group's chance at living zombie free.)

Gene Page/AMCOh Rick. What are you doing?

If you're a fan of the series, and especially the comics, you're probably wondering when the next big villain is coming to town.

Many people think it's Negan, a foul-mouthed, hot headed, tyrannical leader of a group called the Saviors. (We've talked a bit about him here and here.)

However, creator Robert Kirkman previously told us at New York Comic Con in October that it will be a while until we see the fan-favorite from the comics. At a previous Con in Arizona, Kirkman mentioned to fans that we could be waiting around until season 9. Of course, that could have been in jest.

If Negan's not coming soon, who does that leave?

Throughout the past two seasons, the series has been dropping some hints about at least one other group who's around.

You may recall seeing zombies maimed with what looks like the letter W (or M depending on how you look), but no one really seems to know what that means.

Warning: Big potential spoiler ahead.

There are two theories in "The Walking Dead" fandom and online about the marking.

Perhaps the best guess is that this is a nod to The Whisperers, *spoilers* a group who wanderers around wearing masks made out of zombie skin in order to blend in with the dead. *spoilers*

The Whisperers were first introduced in issue 130 which was released August 2014.

Since it's a pretty recent storyline, the group is still shrouded in a lot of mystery. We don't know where they come from, the size of the group, their motives, and if they're necessarily a real danger to Rick and the other survivors.

I've held off on writing about this because it didn't seem relevant to the current progression of the series; however, it was brought to our attention that a fan on imgur made a fantastic connection which ties the present Whisperer storyline in the comics to season 3 of the show.

Basically, you're going to want to head back and re-watch parts of season 3, episode 12 "Clear" before the finale airs Sunday.

In the episode, which aired March 3, 2013, Rick, Michonne, and Carl head back to Rick's hometown in search of guns. There, they find Morgan (Lennie James), the man who took Rick in and told him about the zombie apocalypse back in season one. Gene Page/AMCWhile Morgan now has a big storehouse of guns, he appears to have gone a bit mad. That's understandable considering he lost both his son and wife back to back since the world changed.There's one part in particular fans should revisit in this episode.At one point, Morgan, who doesn't recognize Rick, lunges towards and stabs the series' protagonist. During Morgan's confusion, he shouts out, what, at the time, sounds like a bunch of nonsense. If you revisit the clip now, Morgan actually says something of great value that makes a lot of sense.Rick asks Morgan if he knows him.

Morgan's response is "People wearing dead people's faces."

Rick responds to the claim, but ultimately shrugs it off.

Again, at the time, Morgan's comment sounded like a bunch of gibberish especially since he didn't appear in the best mental state. The Whisperer characters also didn't exist in the comic series at this point.The knowledge of them now changes the context of that line entirely.In season 3, Rick leaves Morgan back in their hometown.Since then, viewers know Morgan's character has reappeared and has been following Rick's trail to catch up with his group.

At the same time, we've been seeing strange markings on trees and have come across the letter "W" on walkers in various episodes.However, if they're not the Whisperers, the show has at least been hinting at some sort of group that is going around wreaking havoc. In season 5, episode 9 the group visited Noah's old home which we learn was ravaged by another group. Written on the back of a wall was a sign that mentioned "wolves not far."

If you go back even further to season 4, the cannibal crew holding Rick's clan hostage mentioned a group that came in and ruined their way of life. A few of them were locked up in a train car. AMCHere's one of the men Rick released from a train car back in season 4. Was he part of this "wolf" group?(Again, not sure if these are people from the same group, but if "The Walking Dead" ties all of that together, you have to admit, it's pretty brilliant.)Either way, people are guessing this "wolf group" may be based on a ruthless and savage group from the comics coined the Scavengers, who, as you could probably guess, are looters who go from place to place taking whatever they can. They're led by a man named Derek, and, in the comics, are in the DC area.

Skybound/Image ComicsHere's one of the first looks at the Scavengers in "The Walking Dead" comic series.

I won't say much more about them here, but we'd be surprised if we don't get a real glimpse at the group behind the "W" markings.If it's not the Whisperers now, "The Walking Dead" has already laid the groundwork for them. At this point, it's seeming more likely we'll see the Scavengers in some iteration. We'll most likely see a brief glimpse of Morgan again, too.One thing's certain. Something big is happening Sunday night during the series' 90-minute season finale. "The Walking Dead" has been building up to it for awhile.

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