For reasons that make absolutely no sense no matter how many rousing speeches Tyrion gives, the council that's formed after Daenerys's death decides to crown Bran Stark king. I'm not sure if it's the worst decision that's ever been made in the history of Game of Thrones, but it's definitely the lowest point in the finale.
"Who has a better story than Bran the Broken? He is our memory. He is the keeper of all our stories," Tyrion says. "Wars, weddings, births, massacres, famines, triumphs, our defeats, our past. Who better to lead us into the future?" When Sansa points out that he can't father any heirs, Tyrion continues. "Good. Sons of kings can be cruel and stupid as you well know . . . that is the wheel our Queen wanted to break. From now on rulers will not be born, they'll be chosen on this spot by the lords and ladies of Westeros to serve the realm."