The author, who is currently working on book six – The Winds of Winter – first released the first instalment, A Game of Thrones, back in the mid-1990s.
Although it didn’t catch on at first, it soon became a huge phenomenon – and, eventually, a wildly successful TV series.
Back in 1999, in an interview resurfaced by fansite Winter Is Coming, Martin identified which characters were initially the toughest for him to write.
And surprisingly given their huge popularity, those he named were Daenerys Targaryen and Jon Snow.
As for the easiest? Tyrion Lannister.
“Tyrion is one character I find very easy to write, as well,” he told Event Horizon’s Flashpoint Weekly Chats.
“The hardest characters are Jon and Dany — in part because they are so removed from the main action, and in part because their chapters have the heaviest ‘magic quotient.’
“As I have said in other interviews, the magic has to be handled very carefully.”
In the same interview, Martin had revealed how taking the shocking decision to kill Ned Stark very early into the story came about.
“I confess, I have always been partial to killing someone important early on, so the readers know you are playing for keeps,” he said.
“We did it on Beauty and the Beast,and we did it in Wild Cards. And of course I have done it here.
“I wish Tolkien had done more of it. Gandalf should have stayed dead.”
Now, Martin is expected to publish The Winds of Winter by the summer of 2020, although no release date has been set.
He’s then got one more novel to write, A Dream of Spring, before A Song of Ice and Fire is finally complete.
The Game of Thrones TV series concluded last month and was met with a hugely divided response among viewers.
To what extent Martin’s own finale will echo that of the TV series, given that it eclipsed the storylines of the books long ago, remains to be seen.