Ser Eyan Whent, also known as the The Yellow Knight, is a minor character in the first, second, third, sixth, seventh and eighth seasons of Game of Thrones. He is a knight from the Riverlands and one of the last members of House Whent following Robert's Rebellion.
After House Tully's reinstatement as Lords of Riverrun, Eyan is chosen as Riverrun's new Master-at-Arms.
Eyan is descended from the main branch of House Whent. He was good friends with Brynden Tully, having known him since Hoster Tully's wedding to Minisa Whent, his cousin. Eyan had always felt more solace with Minisa and her children, and later stayed at Riverrun to help protect Minisa's daughters Catelyn and Lysa during Robert's Rebellion.
After the Rebellion was won, Eyan was wed to Atalyn Wayn. They currently have one child together, a daughter. After Lord Jon Arryn's death, Eyan helps escort Lady Lysa and the new Lord Robin Arryn to the Vale, bringing his wife and daughter with him.
Ser Eyan was present at the Eyrie during Tyrion Lannister's trial, witnessing the death of Ser Vardis Egen.
Ser Eyan overheard a drunk Bolton bannerman during the night of Edmure Tully's wedding at the Twins, learning quickly of the Bolton-Frey-Lannister alliance. Just as the carnage begins, Eyan finds Ser Brynden Tully, and aids in escorting him back to Riverrun.
Ser Eyan remains in the service of Ser Brynden Tully, and helps him retake Riverrun. When Edmure Tully is forced to end the siege and hand Riverrun back to House Frey, Brynden orders Eyan to not fight so that his own life will be spared. Eyan lays down his sword and surrenders. After revealing himself as a Whent, Eyan is imprisoned at the Twins, alongside Edmure.
After the death of Daenerys Targaryen, and House Tully's reinstatement as Lords Paramount of the Trident, Lord Edmure chooses Ser Eyan as his Master-at-arms, seeing an inkling of his own uncle Brynden in him. His wife and daughter are brought from the Vale to Riverrun to live alongside Edmure's own wife Roslin, and their infant son Olyvar.