Ian McShane
News that Ian McShane has been cast in Game of Thrones broke on SaturdayAndreas Rentz/Getty

It's not due to be screened until the spring of 2016. Yet Game of Thrones followers have been given even more to speculate about regarding the sixth season, other than whether Kit Harington will return as Jon Snow, and that is which character new cast member Ian McShane will be playing.

McShane's involvement in the upcoming series was confirmed by Entertainment Weekly on Saturday (1 August 2015), and now rumours have started emerging as to who the Deadwood and Pirates of the Caribbean: On Stranger Tides star will actually be portraying.

Many online theorists have suggested that it could be Randyll Tarly, Samwell's father, after a source told the publication that his part would be of "key importance".

News and fan community site Watchers of the Wall had previously released information on several casting calls that the HBO series producers were holding to fill a number of new parts, with one detailed description sounding very much like Tarly.

The call listed the character as "one of the greatest soldiers in Westeros", and a strict man who "demands martial discipline in the field and in his home". In the first season of Game of Thrones, viewers learned that Samwell was forced into the Night's Watch by his parent after he gave him the ultimatum of either doing so or suffering a "hunting accident", so he certainly fits that bill.

He's never been seen before in the television series, but was mentioned by Stannis Baratheon in the fifth season,calling him "the only man who ever defeated Robert Baratheon", so it does look as if the showrunners are gearing the plot up for him to make an appearance.

However, other speculators on the internet believe that 72-year-old McShane could be playing Euron Greyjoy, also known as Crow's Eye – Theon's uncle and ruthless captain of the Silence, a ship run entirely by men whose tongues he has ripped out to make them all mutes. Greyjoy is said to be a violent and volatile character who is known for his warrior skills and manipulating those around him.

While there's no official news as yet, in terms of appearance McShane could be a good match for either characters mentioned – Tarly being a "balding man with a short, bristly grey beard" and Greyjoy having long, black hair and a dark beard.

British-born McShane made a name for himself in 1980s TV shows Dallas and Lovejoy before landing the lead role of Al Swearengen in popular US Western series Deadwood. He has most recently been seen in American Horror Story: Asylum and Ray Donovan, as well as a handful of movies including Pirates Of The Caribbean: On Stranger Tides, Snow White and the Huntsman, and Jack the Giant Slayer.