3. Olenna Tyrell
I can't praise Dame Diana Rigg enough for her brilliant portrayal as the Queen of Thorns. For this reason, it was truly a pleasure to see her alongside the equally formidable Tywin Lannister, played with similar aplomb by the incomparable Charles Dance. When these two spar it's definitely a chess game between the patriarch and the matriarch of quite possibly the two most powerful families in all of Westeros, and that makes for a riveting watch. Everything that makes Margaery so clever can be attributed to Lady Olenna and I do feel that she isn't the type that sits idly and lets others get ahead. Through her granddaughter's marriage she is one step closer to elevating the her family's status, but I doubt even then that she will let the slightest opportunity get past her. She truly does have one of the most brilliant minds I've seen in the series and I look forward to her season four appearances.