And blowing up half the city to get rid of the religious fanatics? Not only is Tommen now dead, but it's hard to imagine who will fight for a queen willing to massacre anyone to get her way.
Can she actually hang on to the throne? Doubtful, especially considering who's headed her way ...
Daenerys Targaryen
Look who's finally leaving Meereen. The queen of dragons is sailing across the Narrow Sea, headed for King's Landing, and she has quite the army. Who are her allies? She managed to convince the Dothraki to come along on her "wooden horses" and she has ships and fighters courtesy of the Greyjoys. She has an army of Unsullied and she's made powerful friends of the Sand Snakes, in charge of Dorne, and Olenna Tyrell, who will do anything to get revenge on Cersei.
She also has a very strategic adviser in Tyrion, who helped win one battle at King's Landing already. And she has Varys, who probably still has links to his "little birds" and all their intel.
And then, of course, she has some special weapons in Drogon, Rhaegal and Viserion.
At this point, there aren't many against Dany. Even her spurned lover still bows down to her.
Jon Snow
The former Lord Commander is an interesting case. Unlike most people, he could have a legitimate claim to the throne, now that we definitively know he's the son of Rhaegar Targaryen and Lyanna Stark. But will people even believe that outlandish story if Bran ever makes it back to tell them? And even if people do, would Jon Snow even want to sit on the Iron Throne?
He would no doubt make an honourable and fair leader, but he also has conflicted feelings about being in charge. He left the Night's Watch, and when he regained control of Winterfell, he proclaimed Sansa the true heir.
To his shock, all of the Stark bannermen have pledged their allegiance to him, including that adorable, salty Lady Mormont. But it's hard to imagine Jon Snow rallying them to take King's Landing. He knows there are more important battles to fight, and they're going to start in the North.
Petyr "Littlefinger" Baelish
During the season finale, Littlefinger admitted to Sansa that every single decision he makes is based on whether or not it will get him closer to the Iron Throne. He wants to be king, and plans to make Sansa his queen. (Aspiring kings out there, take note: marrying your love interest off to a known sadist isn't a good strategy.) He's awfully far from his goal. He has no claim to the throne, considering his relatively humble background. But he's proven that he's a master manipulator who can turn an unstable situation into chaos. And he clearly thinks Sansa owes him something after he rallied the Knights of the Vale to turn the tides during the Battle at Winterfell.
Euron Greyjoy
He says he wants to rule the Seven Kingdoms, but who are his allies? He seemed to think he could convince Daenerys to marry him, but she doesn't need his ships anymore - if his ships are even built yet.
Gendry
Is he still rowing or what?
- Then again ...
None of this could matter, considering another monarch is also still in the mix. If Tyrion thinks the great game is terrifying, it's only because he hasn't yet locked eyes with the Night's King.