Terry Pratchett, Author and Creator of Fantastical Worlds, Dies at 66

Terry pratchett
British author Terry Pratchett poses for a photo while delivering a petition on behalf of the Alzheimer’s Research Trust outside the front door of London’s 10 Downing Street on November 26, 2008. Suzanne Plunkett/Reuters

Prolific author Sir Terry Pratchett, who wrote over 70 masterful fantasy novels, has died after a long battle with Alzheimer's disease, the BBC reports.

His publisher, Larry Finlay at Transworld Publishers, confirmed the news Thursday morning in a statement, saying that Pratchett had died "with his cat sleeping on his bed and surrounded by his family." Pratchett was 66.

The British author was celebrated for the fantastical worlds depicted in such works as his long-running Discworld series, which he began writing in 1983. The Shepherd's Crown, the 41st volume in the series, was written last summer and is set for release this fall.

Pratchett had been diagnosed with a form of early-onset Alzheimer's back in 2007, and spent the last several years of his advocating in Britain for critically ill patients' right to die.

Friends and admirers took to Twitter on Thursday afternoon to share their respects for the late Pratchett.

Terry Pratchett's writing on death, both in his fiction, and, after his diagnosis, in his essays, meant so very much to me. Rest in power

— Molly Crabapple (@mollycrabapple) March 12, 2015

Terry Pratchett also wrote, "The world is a globe--the farther you sail, the closer to home you are."

— John Green (@johngreen) March 12, 2015

I will miss you, Terry, so much. This is the last thing I wrote about you. http://t.co/YKAFrKjkLc

— Neil Gaiman (@neilhimself) March 12, 2015