Ever since HBO's Game of Thrones first started airing in 2011, the Internet has been rife with countless fan theories about the show's characters, including one that speculates Bran Stark and Daenerys Targaryen are time travelers and another that even suggests the show takes place in the same universe as Friends. As far as author George R.R. Martin is concerned, there is one theory that takes the cake, which suggests that he has actually finished writing the last two books in his A Song of Fire and Ice series.

During an event for his new Game of Thrones companion book, The World of Fire and Ice, George R.R. Martin shot down this conspiracy theory.

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"From my point of view, the craziest one is the people who believe that I've actually finished all of the books, and I'm just sitting on them for some reason in order to get more money or increase the value, you know, to release them at an appropriate point. That's a pretty crazy one, but there seem to be people who actually believe that."

As you may well know, many fans are worried that the Game of Thrones TV series will catch up too quickly to the George R.R. Martin books, five of which are finished. Each season generally spans one book, although Season 4 used events from the third, fourth and fifth books. Series co-creator David Benioff confirmed last week that Bran Stark, played by Isaac Hempstead-Wright, will be sitting Season 5 out, because his story line is already caught up to the books. George R.R. Martin has already confirmed that he won't write an episode in Season 5, as he has for the past four seasons, to concentrate on finishing the books.

As for the fan theories, George R.R. Martin has hinted in the past that some of them are true, although he hasn't confirmed which ones. One said theory is known as R + L = J, which claims that Jon Snow (Kit Harington) may not have been been fathered by Ned Stark (Sean Bean), and another that theorizes who Tyrion's parents really are.

What do you think about these Game of Thrones theories? Chime in with your thoughts below.