The literary world is in mourning today as Terry Pratchett has died at the age of 66.

Best known for the fantasy novel series Discworld, Terry Pratchett announced he had been diagnosed with posterior cortical atrophy, a variant of Alzheimer's disease, in 2007 and continued to write, completing his last book in the summer of 2014. He passed away at home surrounded by his family according to a statement released by his publisher, Larry Finlay, MD at Transworld Publishers.

"I was deeply saddened to learn that Sir Terry Pratchett has died. The world has lost one of its brightest, sharpest minds.

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.

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."

Pratchett's official Twitter account, which he shared with his friend Rob Wilkins shared the news this afternoon with a series of poignant tweets.

Per his website, a Just Giving page donating to the Research Institute to the Care of Older People (RICE) has been set up in his memory.

And if we remember one thing about Pratchett, we should remember his sense of humour.

Image via PJSM Prints/Rob Wilkins