Like her son Joffrey before her, fans of Game of Thrones all agree that Cersei Lannister needs to die, that she needs to die soon, and that she needs to die violently. However, fans still disagree hotly on the logistics and circumstances of this death, debating the big questions like, “How will Cersei die?” and “Who will kill Cersei?” The possibility that Cersei makes it out of the series alive doesn’t even register with most fans, as even George R. R. Martin isn’t that cruel and unjust. After all, we won't feel satisfied by any ending that doesn't promise Westeros a future that is is both peaceful and prosperous.
Most of the fan theories about Cersei Lannister center on a prophecy she heard when she was a teenager from a woods witch named Maggy the Frog. Part of Maggy the Frog’s prophecy was told in the Song of Ice and Fire book series, but it hasn't made it into the show yet. Maggy told Cersei exactly how she is going to die, saying, of Cersei’s children, “Gold shall be their crowns and gold their shrouds. And when your tears have drowned you, the valonqar shall wrap his hands about your pale white throat and choke the life from you.”
Fan theories about the valonqar are understandably numerous, as there are quite a few younger brothers and sisters hanging around in Westeros. Also, due to Cersei’s charming personality, most of those younger siblings have good reason to want her dead. It’s now just a question of who will get their hands on her first.
When Cersei Lannister was a teenager, she and her friend Melara visited a “woods witch” known as Maggy the Frog, who claimed the ability to see the future. Ever since, events in Cersei's life have proven just how accurate these predictions were. Maggy predicted that Melara would die that very night, which came true when the girl drowned in a well. She also prophesied that Cersei would become the queen.
To show off her amazing accuracy, Maggy told Cersei that she would have three golden-haired children, while her King would have 16 of his own. This didn’t seem to make sense at the time, but proved true when Cersei spawned three kids with her brother, Jaime, while her husband, King Robert Baratheon, sired 16 bastards across the Seven Kingdoms.
Since everything else Maggy said has come true, it stands to reason that her predictions regarding Cersei’s death are also unavoidable. Maggy noted that all three of Cersei’s children would die, and that Cersei herself would follow shortly thereafter.
A more popular theory regarding the valonqar is it won't be Tyrion, but the other brother, Jaime, who will slay Cersei. After all, he is the younger twin, said to have come out holding his sister's heel. Both twins have always believed their destinies are tied together, so perhaps Jaime will end Cersei’s evil reign, in a mirror of his infamous king slaying. Reddit user theDarkLordOfMordor lays out a strong case for why Jaime is the most likely candidate, due to his growing disillusionment with his sister/lover.
A popular song in Westeros talks about how “hands of gold are always cold,” and Jaime does have a gigantic golden hand. Would he use it to choke the life from Cersei? Or, as theDarkLordOfMordor theorizes, Jaime will replicate his brother’s actions by using a golden chain to murder his greatest love.
Though the valonqar prophecy speaks of a “little brother,” there is some ambiguity. High Valyrian plays it fast and loose with gender, often using male pronouns when the gender of something is neutral or unclear. Considering this linguistic quirk, Maester Aemon thinks Daenerys Targaryen is the “Prince” That Was Promised. That could open things up to any younger sibling in the story killing Cersei, and Reddit user Lost1127 thinks it will be Arya Stark.
Arya is a trained assassin, and she has pledged to kill Cersei. It’s not a huge stretch to think she will fulfill that promise. In fact, Cersei is the only name still on Arya’s “list” against whom she still has a real vendetta. But how would she do it? Arya could steal the face of one of Cersei’s servants in order to get close enough to kill her—or, for an added layer of dramatic symbolism, steal her beloved brother Jaime’s face before doing the deed.
Part of the reason Cersei Lannister hates her brother Tyrion, aside from her belief he is destined to murder her, is that his complicated birth resulted in the death of their mother, Joanna.
Now that Cersei is pregnant, Reddit user starkravingmad86 predicts that, in a cruel twist, Cersei will suffer the exact same fate as her mother, dying while giving birth to a dwarf. There is obviously precedence for dwarfism in the Lannister family, and this would be a nice bit of payback against Cersei for her prejudice. The child itself could be seen as the valonqar—but so could Jaime, as his impregnation of Cersei would have sealed her demise.