Greatjon Umber

Greatjon Umber, commonly called The Greatjon, is a recurring character in Game of Thrones. He is played by guest star Clive Mantle and débuts in the eighth episode of the first season. The Greatjon is the Lord of Last Hearth and a formidable bannerman of House Stark. He is fighting for Robb Stark in the War of the Five Kings.

Background
The Greatjon is the Lord of Last Hearth and the head of House Umber, a loyal vassal family to House Stark of Winterfell. He is a large, formidable warrior.

Season 1
Robb Stark sends ravens to the bannermen of House Stark instructing them to assemble for a march south to King's Landing to free Eddard Stark. The Greatjon leads a contingent of Umber troops to join the Stark army assembling at Winterfell. He is furious when Robb appoints Galbart Glover to lead the vanguard of the army during a feast at Winterfell. The Greatjon demands the honour for himself and refuses to follow a Glover into battle, threatening to take his troops home. Robb challenges him by saying that he will arrest him as a traitor on his return from the South. The Greatjon draws his knife and Robb's direwolf Grey Wind barrels down the table and knocks him off his feet. Grey Wind bites off two of the Greatjon's fingers. Robb mercifully offers that The Greatjon drew his knife in order to cut his meat for him and the Greatjon laughs off the incident calling Robb's meat tough.

Catelyn Stark joins the army at Moat Cailin. The Greatjon vows that they will smash the Lannisters and march on to King's Landing to rescue Lord Eddard. He objects to Robb releasing a Lannister scout from custody, but Robb exercises his authority and the Greatjon reluctantly accepts his decision. The scout had overestimated the size of Robb's forces.

After hearing of the execution of Lord Eddard, the Greatjon declares that he will never accept any king of House Baratheon as his ruler again, and leads the bannermen of House Stark as well as the Riverlords in proclaiming Robb the King in the North.

Season 2
The Greatjon continues to serve as one of Robb's closest advisors, and is witness to the King explaining his peace terms to Alton Lannister.

In the books
In the Song of Ice and Fire novels, Greatjon Umber is a huge bear of a man who makes for a fierce, loyal friend but a savage and dangerous enemy. He is the Lord of Last Hearth, the northern-most castle of the North bar only the lands held by the Night's Watch. The Greatjon has a son, Smalljon, and two uncles, Mors and Hother (nicknamed 'Crowfood' and 'Whoresbane' respectively).