Petyr Baelish
When Robert travels to Winterfell to name Eddard as his new Hand, Stannis flees to Dragonstone with his forces, including most of the royal navy. Stannis suspects Cersei's involvement in Jon's death. It is later revealed that the true culprit was Jon's wife Lysa, who was persuaded to poison her husband by her lover, Petyr Baelish. Eddard continues Stannis and Jon's investigations, and discovers that Cersei's children are the products of her incestuous affair with her twin brother Jaime Lannister. After Robert's death, Eddard tries to replace Robert's presumed heir Joffrey Baratheon with Stannis, but loses the political struggle against the Lannisters and is executed.