Not much is known about the sixth season of 'Game of Thrones,' but the casting news continues to offer hints about the events that will unfold next year.

Watchers on the Wall has just reported that 'The Borgias' star Pilou Asbæk will join the cast of 'Game of Thrones' as Theon's fearsome uncle Euron Greyjoy. The Danish actor will fill one of the roles that Ian McShane was previously rumored to take, which leads to speculations that McShane will portray Samwell Tarly's father Randyll Tarly.

But who is Euron Greyjoy? And why will his appearance in 'Game of Thrones' mean more difficulties for most characters, especially Daenerys Targaryen?

[SPOILERS AHEAD]

In 'A Song of Ice and Fire,' Euron Greyjoy is also known as Crow's Eye and the captain of Silence, a ship filled with mutes whose tongues have been brutally ripped out. He is a handsome man who wears a patch over his left eye, which Theon claims covers "a black eye shining with malice." In a kingsmoot in 'A Feast for Crows,' he is chosen 'The High King of The Iron Islands' and immediately vows to conquer Westeros by using Daenerys' dragons. Euron sends his brother Victarion to court Daenerys and bring back the dragons using a dragon horn.

Euron Greyjoy is considered a skilled warrior, although he is also known for being ruthless and unpredictable. He once claimed to have a dragon egg which he has lost at sea, and will stop at nothing to take Daenerys' dragons.

But will Euron Greyjoy be a major threat to Daenerys Targaryen in the sixth season of 'Game of Thrones?'

According to Watchers on the Wall, a source claims that the Kingsmoot in Ballintoy Harbour, where people were chanting Euron's name. Crow's Eye could be going after what he wants immediately as soon as he finds out about Daenerys' dragons.

Find out if Euron Greyjoy can take away Daenerys' dragons when the sixth season of 'Game of Thrones' airs on HBO in 2016.