Knight of House Frey

A Knight of House Frey is an unnamed minor character in Game of Thrones. He is played by guest star Patrick Ryan and only appears in the fourth episode of the first season.

Season 1
He is drinking with companions at the Inn at the Crossroads when Tyrion Lannister arrives on his way south. Catelyn Stark is also in the inn and Tyrion recognizes her. She turns to the knights from the Riverlands in the inn to help her to take Tyrion into custody, accusing him of attempting to murder her son Bran Stark. She asserts her origin as a daughter of House Tully and then tells the Knight of House Frey that she knows his sigil and asks after Lord Walder Frey. He reports that Lord Frey is about to celebrate his ninetieth name day and has invited Lord Hoster Tully of Riverrun. Catelyn announces that she will return Tyrion to Winterfell to await the King's justice. The Knight of House Frey draws his sword and threatens Tyrion. Unlike the other men loyal to House Tully from the Inn he does not escort Catelyn further.

In the books
In the Song of Ice and Fire novels, there is a large group of Frey men-at-arms in the inn and Catelyn addresses the Captain of the group.