'Discworld' author Pratchett dies after Alzheimer's battle.

• Position: Living

LONDON -- Fantasy writer Terry Pratchett, creator of the "Discworld'' series and author of more than 70 books, has died. He was 66.

Pratchett, who suffered from a rare form of early onset Alzheimer's disease, had earned wide respect in Britain and beyond with his dignified campaign for the right of critically ill patients to choose assisted suicide.

Transworld Publishers said Pratchett died Thursday at his home, "with his cat sleeping on his bed surrounded by his family.''

According to the BBC, Pratchett's death was announced on Twitter. The first tweet was composed in capital letters, which was how the author portrayed the character of Death in his novels.

"AT LAST, SIR TERRY, WE MUST WALK TOGETHER,'' it stated.

"Terry took Death's arm and followed him through the doors and on to the black desert under the endless night.''

"The End.''

Despite campaigning for assisted suicide after his diagnosis, Sir Terry's publishers said he did not take his own life.

Transworld's managing director Larry Finlay said "the world has lost one of its brightest, sharpest minds.''

Pratchett's ability to write and speak had deteriorated in recent years as the disease progressed. But with his characteristic black fedora and neatly trimmed white beard he remained a familiar figure in the public eye. He completed his final book in the summer of 2014.

Pratchett was best known for "Discworld,'' a series of more than 40 comic novels set in a teeming fantasy world. He has sold more than 65 million books worldwide, and his novels have been translated into several dozen languages.

The author disclosed his condition in 2007. His doctors at first believed he had suffered a stroke, but found him to have an unusual form of Alzheimer's

He tried to be optimistic with his millions of fans, assuring them on his website that the condition didn't seem to be immediately life-threatening.

"Frankly, I would prefer it if people kept things cheerful,'' he said.

As he lost the ability to write on a computer, he turned to a dictation system that allowed him to keep producing fictional works, his agent Colin Smythe said.

"It may have changed his prose style slightly,'' Smythe said. "The real problem is the difficulty of revising it.''

Pratchett didn't shy away from the emotional public debate about assisted suicide.

He used the prestigious Richard Dimbleby lecture in February 2010 to argue the logic of allowing people to end their lives at a time they chose. He said assisted suicide...