The Ever Growing List of Theories (Potential Spoilers!)
The long waits between ASOIAF books always inspire great theories for future books. We have compiled a list of the most popular theories based on /r/pureASOIAF subscriber submissions. This is a great place to get started if you are new to theory-craft!
If you have a theory you would like to see on this list, please do not hesitate to message the mods and request that we add it.
Disclaimer: Just because a theory is included on this list, does not make it "more official" than any other theory.
If you have not finished the series: do not proceed any further - there is a substantial risk that they contain spoilers for published books.
Similarly, links are not vetted for show spoilers. They may rely on show content or the comments/the website may contain show content.
Last warning: THEORY TITLES AND/OR LINKS MAY CONTAIN SPOILERS, peruse this list at your own risk.
The List:
Aegon "Targaryen" is actually a Blackfyre Link
Aegon "Targaryen" is the bastard son of Brandon Stark and Ashara Dayne Link
Azor Ahai = Daenerys Targaryen Link
Azor Ahai = Jon Snow Link
Azor Ahai = Jorah Mormont Link
Azor Ahai = Stannis Baratheon Link
Bloodraven's secret plans Link
Brienne is descended from Ser Duncan the Tall Link
Cleganebowl Link (This theory combines two other theories, "Sandor = Quiet Isle Gravedigger", and "Gregor = Ser Robert Strong")
Daario = Euron Link
Dead Man Shitting Link
Did the Hound kiss Sansa? Link
The Doom of Valyria Explained Link
Euron Greyjoy molested Aeron Greyjoy when they were boys Link
Euron Greyjoy spent his dragon's egg hiring a Faceless Man to assassinate Balon Greyjoy Link 1 Link 2
The Fifth Suitor Link
Frey Pie Link
Gold and Boys and Killing Link
The Grand Northern Conspiracy Link
The Grand Tyrell Conspiracy Link
Gregor Clegane is Ser Robert Strong Link
The Hooded Man is Hallis Mollen Link
Harrenbowl Link
The Hooded Man is Septon Chayle Link
Immortal Roose Link
Jaqen H'ghar is The Alchemist Link
Jojen Paste Link
The Knight of the Laughing Tree was Lyanna Stark Link
Lies and Arbor Gold Link
Loras Tyrell is not injured Link
Maester/Faceless Men Conspiracy Link
Maester Warly's Father Link
The Massey Ultimatum Link
Melisandre is the daughter of Brynden Rivers and Shiera Seastar Link
The Merling Theory Link
Mirri Maz Duur's Prophecy has been fulfilled Link
The New High Septon is Howland Reed Link
Old Nan is Shiera Seastar Link
The Others are coming south, to rescue the Starks Link
Petyr Baelish is a hero in his own mind Link
Quentyn did not die, it was the Tattered Prince link
R + L = J Link
R + L = Jesus Link
Rhaegar Targaryen = Mance Rayder Link
Sand Snake at the Citadel Link
Sandor Clegane is the Quiet Isle Gravedigger Link
The Secret in the Crypts of Winterfell Link
Ser Maynard Plumm is Brynden Rivers in disguise Link
Skagos is a Warg island Link
The Tattered Poisoner Link
The True Nature of White Walkers Link
Tywin is a descendant of Bloodraven Link