Terry Pratchett, the immensely popular British fantasy novelist whose more than 70 books include the series known as Discworld, died on Thursday at his home near Salisbury, England. He was 66.
The cause was posterior cortical atrophy, a rare form of dementia, Suzanne Bridson, an editor at Transworld Publishers, said in an email.
An accomplished satirist with a penchant for sending up cultural and political tomfoolery, Mr. Pratchett created wildly imaginative alternative realities to reflect on a world more familiar to readers as actual reality.
Often spiced with shrewd and sometimes wryly stinging references to literary genres, from fairy tales to Elizabethan drama, his books have sold 85 million copies worldwide, according to his publisher. And though Mr. Pratchett may have suffered from the general indifference of literary critics to the fantasy genre, on the occasions when serious minds took his work seriously, they tended to validate his legitimate literary standing.
In 2003, the novelist A. S. Byatt wrote that critics were paying attention to the Harry Potter books by J. K. Rowling but rarely to other fantasists.
“They do not now review the great Terry Pratchett,” Ms. Byatt wrote, “whose wit is metaphysical, who creates an energetic and lively secondary world, who has a multifarious genius for strong parody as opposed to derivative manipulation of past motifs, who deals with death with startling originality. Who writes amazing sentences.”
Mr. Pratchett’s primary setting, Discworld, is a planet of sorts, Frisbee-like in shape and balanced on the backs of four elephants who themselves stand upon the shell of a giant turtle.
Mr. Pratchett introduced it in 1983 in the novel “The Colour of Magic.” Its protagonist, Rincewind, one of a number of recurring characters in the series, is a feckless wizard-wannabe who was an unsuccessful student at Unseen University, the principal school for wizards in the city-state of Ankh-Morpork.
Over three decades and 40 or so volumes (a handful of which were aimed at young readers), Discworld grew into a multilayered society inhabited by witches, trolls and other creatures of varying personalities and powers who often seem to re-enact the follies of Englishmen and other Earth people. Death was a character in almost all of the Discworld books, speaking in all capital letters and expressing a fascination with humans.
Mr. Pratchett often wrote with eyebrow arched and tongue planted firmly in cheek; in the behavior of his mythical creatures it was hard to miss the barbs being tossed in the direction of humanity.
“Of course, Lord Vetinari, Patrician of Ankh-Morpork, would occasionally meet Lady Margolotta, Governess of Uberwald,” he wrote in the most recent Discworld book, “Raising Steam” (2013). “Why shouldn’t he? After all he also occasionally had meetings with Diamond King of Trolls up near Koom Valley, and indeed with the Low King of the Dwarfs, Rhys Rhysson, in his caverns under Uberwald. This, as everybody knew, was politics. Yes, politics, the secret glue that stopped the world falling into warfare.
“In the past,” he continued, “there had been so much war, far too much, but as every schoolboy knew, or at least knew in those days when schoolboys actually read anything more demanding than a crisp packet, not so long ago a truly terrible war, the last war of Koom Valley, had almosthappened, out of which the dwarfs and trolls had managed to achieve not exactly peace, but an understanding from which, hopefully, peace might evolve. There had been the shaking of hands, important hands, shaken fervently, and so there was hope, hope as fragile as a thought.”
Mr. Pratchett learned he had posterior cortical atrophy in 2007. A degeneration of the outer layer of the brain, the condition may be a variant of Alzheimer’s disease. He gave interviews and speeches about his condition, which he referred to as “an embuggerance.” In 2008 he contributed $1 million to Alzheimer’s research. He was also an outspoken advocate for the legalization of assisted suicide.
He became Sir Terry when Queen Elizabeth II knighted him as 2008 turned to 2009.
In a Twitter post on Thursday, David Cameron, the British prime minister, said Mr. Pratchett’s had “fired the imagination of millions” with his books and had “fearlessly campaigned for dementia awareness.”
Terence David John Pratchett was born on April 28, 1948, in Beaconsfield, Buckinghamshire, northwest of London, to David Pratchett, an engineer, and the former Eileen Kearns. He did not finish school and was fond of saying that he had received his best education at the Beaconsfield Public Library. An early interest in astronomy spurred his reading of science fiction. He worked as a journalist for a newspaper in Buckinghamshire and in 1971 published his first novel, “The Carpet People,” about a tribe, known as Munrungs, that lives on a vast carpet.
Mr. Pratchett’s other books include “The Unadulterated Cat,” an illustrated (by Gray Jolliffe) collection of cat anecdotes; “Good Omens,” a comic fantasy about the birth of the son of Satan, written with Neil Gaiman; “The Dark Side of the Sun,” a science-fiction novel; and “Dodger,” a novel for children set in Victorian England and inspired by Dickens.
He is survived by his wife, the former Lyn Purves, and a daughter, Rhianna.
Three Twitter posts on Mr. Pratchett’s account on Thursday described his demise in imitation of his fiction.
“AT LAST, SIR TERRY, WE MUST WALK TOGETHER,” the first said.
“Terry took Death’s arm and followed him through the doors and on to the black desert under the endless night,” the second said.
The third said simply, “The End.”