25. Olenna Tyrell

Time of death: Season 7, episode 3, "The Queen's Justice"

Cause of death: Cersei wants to give Olenna a cruel death after taking Highgarden, but Jaime convinces her otherwise and he gives Olenna poison.

Sadness ranking: 6. Olenna goes down memorably. Right after she drinks the poison, she confesses to Jaime that she was the one who poisoned Joffrey, and she wants Cersei to know it. She made death look so cool, but it's sad to see her go.