LONDON (Reuters) - Terry Pratchett, the British author whose fantasy novels sold in their tens of millions worldwide, has died of a form of Alzheimer's disease aged 66, his publisher said on Thursday.
News about the death of Pratchett - who campaigned during his final illness for legalizing assisted death - came on his Twitter account in a series of tweets written in the style of his Discworld novels, where Death always talks in capital letters.
"AT LAST, SIR TERRY, WE MUST WALK TOGETHER," said the first tweet on @terryandrob. "Terry took Death's arm and followed him through the doors and on to the black desert under the endless night," said the second, while a third read simply: "The End".
Pratchett died at home surrounded by his family with his cat sleeping on his bed, Transworld Publishers said.
The author, who wore a trademark broad-brimmed black hat, was diagnosed in 2007 with posterior cortical atrophy, a progressive degenerative condition. Continuing to write, he completed his last book, a new Discworld novel, in the summer of 2014 before succumbing to the final stages of the disease.
Pratchett gave numerous interviews and lectures in which he spoke frankly about his disease - and his love of 16th century English composer Thomas Tallis.
"I would like to die peacefully with Thomas Tallis on my iPod before the disease takes me over and I hope that will not be for quite some time to come, because if I knew that I could die at any time I wanted, then suddenly every day would be as precious as a million pounds," he said in 2010.
"If I knew that I could die, I would live. My life, my death, my choice."
Prime Minister David Cameron said on Twitter: "His books fired the imagination of millions and he fearlessly campaigned for dementia awareness".
Literary figures also expressed their sadness. Canadian author Margaret Atwood wrote: "I vastly enjoyed his playful, smart Discworld books."
His publishers said the world had lost "one of its brightest, sharpest minds". "In over 70 books, Terry enriched the planet like few before him," said Larry Finlay, managing director at Transworld, a division of Penguin Random House.
"As all who read him know, Discworld was his vehicle to satirize this world. He did so brilliantly, with great skill, enormous humor and constant invention," he said.
A unique creation, Discworld is a circular world set on the backs of four elephants standing on the shell of a giant turtle, populated by a vast and colorful cast of characters inspired by the worlds of fantasy, folk tales and mythology.
Pratchett used Discworld to parody those genres, but also to send up aspects of modern life by drawing often incongruous connections between his imaginary world and things ordinary people living in 20th century Britain would recognize.
Selections of Pratchett's quotes quickly appeared on British newspaper websites while fans exchanged their favorite quips from Discworld characters online.
This was one popular example:
"DON'T THINK OF IT AS DYING," said Death. "JUST THINK OF IT AS LEAVING EARLY TO AVOID THE RUSH."
(Editing by Michael Holden, Guy Faulconbridge and David Stamp)