So, I'm probably incredibly late to the party, and most likely most of you already know about this and will just wave over it, but I'm still gonna bring this up, because this could be really interesting discussion to see if we can predict who will sit on the World's Most Uncomfortable Chair. Just a heads up, I'm not a historian nor an Englishman, so this is based solely on the research I found on the Internet:

Game of Thrones, and of course its book counterpart, is an alternative history of the War of the Roses - a series of wars for control of the throne of England. Conflict between the Starks and the Lannisters the Yorks and the Lancasters ends with the victory of the latter House.

We start with King Henry VI. He was rumoured to be insane, feeble-minded, experienced several mental breakdowns, so people began to challenge his reign. It's not very hard to draw a parallel between Henry VI and the Mad King Aerys II Targaryen.

During the War (parallel to Robert's Rebellion) there were two very short-reigning kings, Edwards IV and V, before the War of the Roses ended with Henry VII won the throne by defeating King Richard III at the Battle of Bosworth Field.

(On a side-note, Richard III was portrayed by the Tudor scholars as a deformed and was the subject of many attacks... Tyrion Lannister, anyone?)

So now we enter the Tudor era with Henry VII who, when compared to the world of Westeros, reflects Robert Baratheon. Henry VII was called the usurper, supports the Lancasters, but ends up marrying Elizabeth of York (In this role, Lyanna Stark?). They wind up having the son we know as Henry VIII. In his youth, Henry VIII was a celebrity. Athlete, expert jouster, popular with the ladies, cultured... Well, we all know how he ended up. Basically the fallen hero. So now we see that Robert Baratheon has traits of both Henry VII and Henry VIII. Although, seeing how Henry VIII was a cruel king, most of us would make a connection between him and Joffrey, so how do we explain that?

Henry VIII legitimized only one of his bastard children - Henry FitzRoy - whom he got from an affair with Elizabeth "Bessie" Blount. And remember Robert in season 1? "Bessie! Thank the gods for Bessie..." FitzRoy died really young by disease (on paper), but it was speculated that he was poisoned.

After Henry VIII, his son - Edward VI - inherits the throne. In the world of Westeros, this is Tommen Barahtheon. Edward inherits the throne very young, he is gullible and is pushed around, mostly by the family from his mother's side. After Edward, for a very short time the country is ruled by Lady Jane Grey, the Nine-Day Queen, until she was thrown into the Tower and... off with her head. Now, there might've been small parallel between Lady Grey and Margery Tyrell, but that would be stretching.

WARNING, WE'RE MOVING INTO THE SPOILER TERRITORY! THIS IS YOUR LAST CHANCE! SPOILERS AHEAD! YOU HAVE BEEN WARNED!

In the Season 6 finale, what a shocker - everybody dies, and Cersei Lannister becomes the Queen of the Seven Kingdoms. In English history, there is another cruel woman who claimed the throne after Lady Grey had been executed, and the parallel is really evident
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Mary I Tudor, AKA Bloody Mary. I think most of you have heard of the good lady.

And this is where predictions and speculations start. After Bloody Mary, another woman sits on the throne - Good Queen Bess, the Virgin Queen, Elizabeth I. Who might this be, in the world of Westeros? My best guess would be Sansa Stark.

After Elizabeth, the throne is claimed by James VI of Scotland, who becomes James I of England. Since Scotland is the closest thing to the Wall and the North I can imagine, I would assume Jon Snow (current King in the North), would eventually claim the throne.

But those are just my predictions. Questions? Comments? Let the discussion begin!