Warning: There are spoilers ahead for "Game of Thrones" as well as speculation regarding potential future events. 

We won't see "Game of Thrones" season six until well into next year, but rumors of what will happen in season six are already well underway. 

Among them is one you can always count on which has to deal with a character long gone.

Fans of the series always wonder when and if Lady Stoneheart is going to make an appearance on the HBO show.

Stoneheart is the given name to the resurrected character of Catelyn Stark. We're now in full season six mode, and, as fans have seen every season, unnamed sources are claiming that Stoneheart will be featured. But the top two fan sites dedicated to "Game of Thrones" news are divided on whether there's any base to this claim. 

For show-only fans, this may be a bit confusing.

We'll explain.

In the third book, "A Storm of Swords," the shocking Red Wedding takes place, where Robb Stark was betrayed and murdered. Robb, the son of Ned and Catelyn Stark, had proclaimed himself King in the North, and allied with the Frey family in direct opposition to the Lannisters. But the Freys double-crossed Robb, and paired up with the Lannisters to trap Robb and his entire army in a brutal massacre. The traitorous Freys didn't stop with Robb — they cut Catelyn's throat, and threw her dead body into a nearby river. In the show, this is where her story was left. 

But in the books, just a hundred pages after the Red Wedding takes place, author George R.R. Martin threw a huge curve-ball in the narrative. Catelyn Stark's body is found by a group of rebels, among whom is a fire priest named Thoros of Myr. He uses magic to resurrect her body, and Catelyn is reborn as a zombified version of herself. She now goes by the name Lady Stoneheart.

Lady Stoneheart is a hollowed version of Catelyn, unable to speak clearly (due to her slit throat). But her mission is clear: Exact revenge on those who wronged her family. She takes charge of the rebel group, known as the Brotherhood without Banners, and begins capturing and hanging men who belong to the families responsible for the death of her son, Robb. 

This is insane, right? It also sounds like it would make for great television. But Lady Stoneheart has yet to make an appearance on the show. If the show was following the exact timeline of the books, she should have been introduced around the season three finale or the very beginning of season four. 

Book readers immediately began speculating Stoneheart may appear in the season three finale, which was titled "Mhysa"— a Valyrian word for "mother." But no dice. The season concluded with a lot of disappointment from those wanting a glimpse of Stoneheart on screen. 

Enthusiasts figured season four would be as good a time as any to see Stoneheart unleashed. The show had begun diverging from the books' timeline anyways, so it made sense. 

Season four aired. Fans got pumped when actress Lena Headey, who plays Cersei Lannister, posted this photo on Instagram with the caption "My stone heart."

The photo appeared around the middle of season four, with just three episodes left in the season. Book readers were convinced this was it. Stoneheart was finally coming. The finale episode for season four was titled "The Children." Stoneheart's revenge is motivated by her dead children. It was all coming together.

But the season came to an end, and still no Stoneheart. The director of the finale, Alex Graves, had to explain to viewers Stoneheart was never even on the table for season four. The actress who plays Catelyn, Michelle Fairley, said in an interview about the Stoneheart letdown: "Yeah, the character’s dead. She’s dead."

Undeterred, some Stoneheart hopefuls still believed it was all a ruse. Surely she would come in season five.

Same story, slightly different ending.

The final episode of season five was titled "Mother's Mercy." Fans felt like the showrunners know fans are on the lookout for any possible signs. One Reddit user, CerealSlayer, pointed out in the appendix of "A Feast for Crows" (AFFC), Lady Stoneheart's entry states she is sometimes called Mother Mercy. 

Once again, the "hype train" rolled into the station. And fans jumped aboard.

Season five ended. No Stoneheart. 

Two full seasons have come and gone, with no confirmation Lady Stoneheart is set to return. But fans continue scouring the internet for clues their vengeful zombie-Catelyn will exist on screen. 

So now, in the lull between seasons five and six, the rumor mill is cranking again. At the end of August, this tweet sent fans into an excited panic:

The account, Irish Thrones, is an Ireland-based channel that typically posts photos of set locations and "Game of Thrones" signage around Northern Ireland, where a large chunk of the show is filmed. 

The tweet was immediately spotted by two of the biggest "Game of Thrones" fan sites: Winter is Coming and Watchers on the Wall.  

Winter is Coming called the account a "rock star," and posted the rumor onto their site. 

@IrishThrones this is huge. You guys are rock stars! :)

— Winter is Coming (@WiCnet) August 29, 2015

But Watchers on the Wall was more skeptical.

@IrishThrones You're going to have to back that up with some more info. That's a pretty steep claim.

— Watchers on the Wall (@WatchersOTWall) August 29, 2015

They reported the tweet as false, citing "all our top sources say no." Editor-in-chief of the site, Susan Miller, posted several tweets about the rumor as well. 

So the cycle is in motion again.

Some fans believe the hype.

Others are tired of the idea. 

There is a chance that showrunners David Benioff and D.B. Weiss have no intention of including Stoneheart. Then again, they could be waiting for a more opportune moment in the series' pacing. One thing is certain — until the entire show has aired, there will always be another round of Stoneheart rumors.  

Join the conversation about this story »

NOW WATCH: This crazy old 'Game of Thrones' theory just made a big comeback, and fans are losing it