Terry Pratchett, whose Discworld series of fantasy novels sold over 80 million copies worldwide, has died following a lengthy battle with Alzheimer’s disease. He was 66. He was one of Britain’s most beloved authors and was the UK’s bestselling author throughout the 1990s. Pratchett, who was knighted by the Queen in 2009, saw a number of his works adapted for film and TV, including Hogfather in 2006 and Going Postal in 2008.

“In over 70 books, Terry enriched the planet like few before him. As all who read him know, Discworld was his vehicle to satirize this world: He did so brilliantly, with great skill, enormous humour and constant invention,” said Transworld Publishers’ Larry Finlay.

“Terry faced his Alzheimer’s disease (an ’embuggerance’, as he called it) publicly and bravely. Over the last few years, it was his writing that sustained him. His legacy will endure for decades to come.

“My sympathies go out to Terry’s wife Lyn, their daughter Rhianna, to his close friend Rob Wilkins, and to all closest to him.”

Despite his illness, Pratchett continued writing, completing his final novel The Shepherd’s Crown last year. His passing was announced via Pratchett’s own Twitter account with a series of tweets, culminating with the suitably final, “The End.”