Game Of Thrones season 6 spoilers: Bran Stark's return, Euron Greyjoy introduction and all you need to know

After the shocking ending of Game Of Thrones' season five that got everyone in a bit of a theory frenzy, fans of the series cannot help but speculate nabout Jon Snow's future and what will happen in other aspects of the storyline.

Now that George RR Martin's books and the television series have somewhat reached the same point in characters' plots, it is anyone's guess what will happen next, and fans have certainly begun to make up their own theories.

Online viewer community, Watchers On The Wall, recently revealed that the casting calls sent out for the shows have already been leaked, accompanied by some in-depth descriptions that seem very indicative of existing characters readers of the sagas (and close followers of the series) will already know.

One of the more obvious casting requests seems to fit the bill of the youngest member of the House Stark, Rickon, who we last saw in season three heading to The Last Hearth in search of safe refuge to wait out until one day, he can return as the heir of Winterfell. Given Sansa Stark's unexpected escape from Ramsey's clutches in the season five finale, and that she found out her sibling was still alive earlier on in the season, it makes sense that the two may reunite at some point soon.

Given that the actor originally played him, Art Parkinson, has had a huge growth spurt as of late (seen most recently in movie San Andreas), it's understandable that the show would want to recast the role of Rickon, and the same goes for Bran Stark – an equally young character also set to be returning in season six after a season away.

His absence in the show's latest season was due to the fact that his storyline had already reached up to where Martin's latest book, A Dance With Dragons, left off, whereas the other characters in Game Of Thrones had not... yet. But now that everyone is up to speed, the writers are forced to start building their own plotlines, meaning that Bran can make a comeback.

At the time that it was announced whether Bran would have made an appearance in season five, after what was described by fans as a drawn-on storyline involving Bran in the fourth, David Benioff spoke out about the decision to not drag his character into season six.

"He's now entering a training period which is going to take quite some time, much of which isn't particularly cinematic. So rather that being stuck in a cave for a year, we figured it would be interesting to leave him out for a little bit," he explained. But he didn't want to reveal anything more than that. Basically, we can't wait to see what they've done with the Stark warg, because by the sounds of things, it is going to be good!

Another character that the casting calls hint might be returning to the show is Jon Umber, commonly called the Greatjon, someone that viewers have not since season one. He would currently be harbouring Rickon if the existing storylines are still being followed, despite the evident recasting, so his reintroduction ties in well with other characters rumoured to be returning.

One last character that viewers won't have seen before but readers of the A Song Of Ice and Fire saga will be familiar with is Euron Greyjoy (Theon's uncle). The casting call describes the role obscurely as simply a pirate but big fans of the series will know that Euron captains a ship in the novels so it is a strong indication that it could be him who will feature in the upcoming season.

Like Sansa, Theon fled Winterfell to rid himself of Ramsey's torturous ways, so the introduction of another Greyjoy would also tie in with what happened in the season five finale. Could Theon meet his uncle as he makes his escape with Sansa? Will that be the catalyst to him remembering who he really is, despite Ramsey's conditioning?

There seem to be a lot of new characters coming our way in April 2016, (which is when season six is meant to start airing) as other parts to be filled included a "Leading Actress", "Priestess" and "Fierce Warrior", as well as three different young boys that some have speculated could be a young Ned Stark given their role description. But those are only the vague ones...

One call's description indicates strongly that Randyll Tarly (Samwell Tarly's father) will feature in the show, seeing as they asked for an actor in between 50 and 60 and described the role as one of the greatest soldiers in Westeros, which fits his character.

A stern man, he demands martial discipline in the field and in his home. The call continues to describe the role as "a very good part" in next year's season and that states he is "centrally involved" in a protagonist's storyline. Alongside this very specific casting call, there were also three more vague ones linked that could be talking about Samwell's mother, brother and sister.

Much like Rickon's reintroduction to the show, Samwell's family's involvement in season six makes perfect sense given that he was sent away from The Night's Watch by Jon Snow in the season five finale. Perhaps his family's resting place is where he ended up?

It is not just new characters that fans are wondering about though. The last time we saw Daenerys, she had been dropped into a particularly hostile looking Dothraki desert after Drogon decided to fly her back to his place of origin. Many viewers believe that the Mother Of Dragons might be able to convince her onlookers to become her Dothraki army, in a further attempt to reclaim the Iron Throne – and that particular fan theory doesn't sound too farfetched given her current predicament.

Now, the main speculation that everyone has been discussing is whether the showrunners are planning on bringing Jon Snow back for season 6, or whether they even can, in some kind of capacity. Some even believe he may return as a white walker or alternatively not even been killed at all.

Leaked photos of the well-loved character emerged shortly before the episode of his demise depicting him with white eyes, which, if they are real, could foreshadow the idea of Snow becoming a warg like his brother, Bran and living on through his direwolf Ghost. Given that the prologue to A Dance With Dragons is about a warg attempting that same act and that it is eluded multiple times in the books that all of the Stark children possess the same powers, combined with Martin's penchant for foreshadowing, it seems pretty clear that's what he's intending to do with Snow's character in the literature. Will the TV writers follow the evolving pattern?

These rumours could be just that though, considering that in a recent interview Kit Harington stated: "I've been told I'm dead. I'm dead. I'm not coming back next season. So that's all I can tell you, really." Although, they wouldn't necessarily have to have Harington back if the character was now a direwolf we suppose?

We are sure that until next spring, more and more will be revealed involving the characters of Westeros, with some information confusing the fan theories in true Game Of Thrones fashion. So until the season premiers in April, we can never know for certain what will happen, we will just have to wait and see!